Interface: Define extension-side ProvisioningProvider interface

[wbreza]

Summary

Define the ProvisioningProvider interface and ProvisioningProviderFactory type in pkg/azdext/ that extension authors implement to provide custom provisioning providers. This mirrors the core provisioning.Provider contract but uses proto types and adds explicit progress reporter parameters.

Parent Epic

Part of #7465 — Provisioning Providers in the AZD Extension Framework

Context

Extension authors need a clean Go interface to implement. The interface mirrors the core provisioning.Provider but differs in key ways:

1. No Name() method — the name is set during registration via WithProvisioningProvider(name, factory), not returned by the provider at runtime
2. Progress reporter parameters — Deploy, Preview, Destroy take a ProgressReporter for in-band progress streaming (the core interface doesn't have this because core providers handle progress internally)
3. Proto types — all parameters and return values use proto-generated types, not core domain types

Existing Patterns

• ServiceTargetProvider interface in pkg/azdext/service_target_manager.go
• FrameworkServiceProvider interface in pkg/azdext/framework_service_manager.go

Detailed Requirements

type ProvisioningProvider interface {
    Initialize(ctx context.Context, projectPath string, options *ProvisioningOptions) error
    State(ctx context.Context, options *ProvisioningStateOptions) (*ProvisioningStateResult, error)
    Deploy(ctx context.Context, progress ProgressReporter) (*ProvisioningDeployResult, error)
    Preview(ctx context.Context, progress ProgressReporter) (*ProvisioningDeployPreviewResult, error)
    Destroy(ctx context.Context, options *ProvisioningDestroyOptions, progress ProgressReporter) (*ProvisioningDestroyResult, error)
    EnsureEnv(ctx context.Context) error
    Parameters(ctx context.Context) ([]*ProvisioningParameter, error)
}

type ProvisioningProviderFactory func() ProvisioningProvider

Where ProgressReporter is the same type used by service targets/framework services (typically a function that sends progress messages).

Acceptance Criteria

• ProvisioningProvider interface defined with all 7 methods
• ProvisioningProviderFactory type alias: func() ProvisioningProvider
• No Name() method on the interface
• Deploy, Preview, Destroy accept ProgressReporter parameter
• All parameter/return types use proto-generated types
• Follows naming conventions of ServiceTargetProvider and FrameworkServiceProvider

Dependencies

• Codegen: Generate Go code from provisioning.proto #7467 — Generated Go types must exist

Files

• Create/Modify: pkg/azdext/provisioning_manager.go (interface definition at top of file)