test : add parser unit tests for sqli_checker plugin

[tmdeveloper007]

Summary of What Needs to be Done:
Add parser and contract unit tests for the sqli_checker plugin. The plugin parses SQL injection checker output to extract injectable vectors. Tests should cover normal parsing, database enumeration detection, empty output, malformed output, and the executor normalization path.

Changes that Need to be Made:

• Create testing/backend/unit/test_sqli_checker_plugin.py following the existing plugin test pattern
• Create testing/backend/unit/fixtures/sqli_checker/sample_output.txt with representative sqli-checker output
• Import the real parser from plugins/sqli_checker/parser.py
• Test: metadata loads through PluginManager validation path
• Test: build_command renders representative target
• Test: parser.parse on sample output with payloads produces expected findings
• Test: parser.parse on empty output returns empty findings
• Test: parser.parse on output with database enumeration header extracts DB names
• Test: executor._normalize_parsed_result on fixture output

Impact that it would Provide:

• Regression coverage for SQL injection vector extraction
• Ensures injectable parameters are correctly identified and surfaced
• Faster CI via targeted plugin allowlist

Note: This task is being handled by tmdeveloper007 — please assign to that account when picking it up.

[aaniya22]

pls assign this to me under gssoc