Add directives on directive definitions to the Language layer

[glen-84]

Summary

Adds the HotChocolate.Language (AST/parser/printer/visitor) support for directives on directive definitions (graphql/graphql-spec#1206, issue #4625), the first of three stacked PRs. Purely additive to the syntax layer; no behavior change for documents that don't use the new syntax.

• DirectiveDefinitionNode gains a Directives collection (parsed between the argument definitions and the repeatable keyword, per the grammar) with constructor, WithDirectives, GetNodes, equality/hashing, and printing support.
• New DirectiveExtensionNode (SyntaxKind.DirectiveExtension) for extend directive @foo @applied, wired through the parser, printer, visitor, walkers, rewriter, and navigator.
• New DIRECTIVE_DEFINITION value on the string-based Language.DirectiveLocation.

Test plan

• Parser tests: directives on definitions (with/without arguments, with repeatable), extend directive parsing, and the grammar's directives-required rule for extensions.
• Printer round-trip tests (indented + non-indented) and a parse→print→reparse equality test, plus an indented snapshot.
• Node equality/hashing and GetNodes coverage for both node types; visitor/rewriter/navigator-coordinate coverage for DirectiveExtensionNode.
• Full HotChocolate.Language suite green: 2703 passed, 0 failed (3 pre-existing skips) on net8.0/9.0/10.0.

[Copilot]

Pull request overview

Adds GraphQL SDL syntax-layer support in HotChocolate.Language for (1) directives applied to directive definitions and (2) extend directive extensions, aligning the AST/parser/printer/visitor pipeline with the updated GraphQL spec draft.

Changes:

• Extended DirectiveDefinitionNode with a Directives collection and updated parsing/printing/equality/rewriting to include it.
• Introduced DirectiveExtensionNode (SyntaxKind.DirectiveExtension) and wired it through parser, serializer/printer, visitors/walkers/rewriter, and navigator coordinates.
• Added/updated unit tests and snapshots to cover parsing and round-tripping of the new syntax.

Reviewed changes

Copilot reviewed 31 out of 31 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/HotChocolate/Utilities/src/Utilities.Introspection/IntrospectionFormatter.cs	Passes empty directives list when constructing DirectiveDefinitionNode.
src/HotChocolate/Language/test/Language.Tests/Visitors/SyntaxVisitorTests.cs	Adds visitor coverage for DirectiveExtensionNode.
src/HotChocolate/Language/test/Language.Tests/Visitors/SyntaxRewriterTests.cs	Adds rewrite coverage for directives inside directive extensions.
src/HotChocolate/Language/test/Language.Tests/Parser/DirectiveParserTests.cs	Adds parser tests for DIRECTIVE_DEFINITION, directives on directive definitions, and extend directive.
src/HotChocolate/Language/test/Language.Tests/Parser/snapshots/KitchenSinkParserTests.ParseFacebookKitchenSinkSchema.snap	Updates snapshot to include new Directives field on directive definitions.
src/HotChocolate/Language/test/Language.SyntaxTree.Tests/Utilities/SchemaSyntaxPrinterTests.cs	Adds printer round-trip and indentation tests for new SDL forms.
src/HotChocolate/Language/test/Language.SyntaxTree.Tests/Utilities/snapshots/SchemaSyntaxPrinterTests.Serialize_DirectiveDefWithDirectivesAndExtension_OutHasIndentation.snap	New snapshot for indented printing including directive directives + directive extension.
src/HotChocolate/Language/test/Language.SyntaxTree.Tests/DirectiveExtensionNodeTests.cs	New unit tests for DirectiveExtensionNode construction, nodes enumeration, and equality/hashing.
src/HotChocolate/Language/test/Language.SyntaxTree.Tests/DirectiveDefinitionNodeTests.cs	Updates existing tests for new ctor arg; adds tests for directive-definition directives.
src/HotChocolate/Language/src/Language.Visitors/SyntaxWalker~1.Leave.cs	Adds DirectiveExtension dispatch + virtual hook (generic walker).
src/HotChocolate/Language/src/Language.Visitors/SyntaxWalker~1.Enter.cs	Adds DirectiveExtension dispatch + virtual hook (generic walker).
src/HotChocolate/Language/src/Language.Visitors/SyntaxWalker.Leave.cs	Adds DirectiveExtension dispatch + virtual hook (non-generic walker).
src/HotChocolate/Language/src/Language.Visitors/SyntaxWalker.Enter.cs	Adds DirectiveExtension dispatch + virtual hook (non-generic walker).
src/HotChocolate/Language/src/Language.Visitors/SyntaxVisitor~1.VisitationMap.cs	Ensures visitor traverses directive-definition directives; adds traversal for directive extensions.
src/HotChocolate/Language/src/Language.Visitors/SyntaxRewriter~1.cs	Adds rewrite support for directive-definition directives and directive extensions.
src/HotChocolate/Language/src/Language.Visitors/DefaultSyntaxNavigator.cs	Includes directive extensions in schema coordinate creation.
src/HotChocolate/Language/src/Language.Utf8/Utf8GraphQLParser.Extensions.cs	Parses extend directive @name ... as a type system extension.
src/HotChocolate/Language/src/Language.Utf8/Utf8GraphQLParser.Directives.cs	Parses directives on directive definitions (between args and repeatable).
src/HotChocolate/Language/src/Language.SyntaxTree/Utilities/SyntaxSerializer.SchemaSyntax.cs	Prints directives on directive definitions and prints directive extensions.
src/HotChocolate/Language/src/Language.SyntaxTree/Utilities/SyntaxSerializer.cs	Adds serializer dispatch for directive extensions (definition + top-level).
src/HotChocolate/Language/src/Language.SyntaxTree/SyntaxKind.cs	Adds SyntaxKind.DirectiveExtension.
src/HotChocolate/Language/src/Language.SyntaxTree/SyntaxEqualityComparer.cs	Adds equality/hash support for directive extensions and directive-definition directives.
src/HotChocolate/Language/src/Language.SyntaxTree/DirectiveLocation.cs	Adds DIRECTIVE_DEFINITION location constant.
src/HotChocolate/Language/src/Language.SyntaxTree/DirectiveExtensionNode.cs	Introduces new AST node for directive extensions.
src/HotChocolate/Language/src/Language.SyntaxTree/DirectiveDefinitionNode.cs	Adds Directives collection + API surface updates.
src/HotChocolate/Fusion/src/Fusion.Execution.Types/Completion/CompositeSchemaContext.cs	Updates directive definition construction to include empty directives list.
src/HotChocolate/Fusion/src/Fusion.Execution.Types/Completion/CompositeSchemaBuilder.cs	Updates directive definition construction to include empty directives list.
src/HotChocolate/Core/src/Types.Abstractions/Serialization/SemanticNonNullSchemaRewriter.cs	Updates directive definition construction to include directives: [].
src/HotChocolate/Core/src/Types.Abstractions/Serialization/SchemaFormatter.cs	Updates directive definition construction to include empty directives list.
src/HotChocolate/Core/src/Types.Abstractions/Serialization/SchemaDebugFormatter.cs	Updates directive definition construction to include empty directives list.
dictionary.txt	Adds reparsed to dictionary.

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