Draft: Security monitoring feature parity with Agent V2

[kamalchaturvedi]

Proposed changes

Commit 1:
The securityviolationsprocessor now processes NGINX App Protect WAF syslog messages, and transforms them into SecurityViolationEvent protobuf messages. This protobuf definition replaces the existing struct definition in /internal folder. This was done to allow management-plane to import this schema as a contract for handling security violations.

Commit 2:
Additionally, added the following capabilities to the parsing the details extraction from raw violations, to bring the feature in parity with Agent V2 implementation:

1. Parses XML violation details with context extraction (parameter, header, cookie, uri, request)
2. Extracts attack signature details

Commit 3:
These changes were thoroughly tested with addition of /testdata in Agent V2 implementation (https://github.com/nginx/agent/tree/dev-v2/src/extensions/nginx-app-protect/monitoring/processor/testdata) and additional variety of violations, to ensure robust coverage.

Checklist

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• I have read the CONTRIBUTING document
• I have run make install-tools and have attached any dependency changes to this pull request
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• If applicable, I have updated any relevant documentation (README.md)
• If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13

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