Add LlvmLinkerParser for LLVM lld linker error parsing

[sgscheffler]

Summary

Add LlvmLinkerParser for LLVM lld linker error parsing

Changes

• Add LlvmLinkerParser class for parsing ld.lld error messages
• Support versioned linkers (ld.lld-15, etc.)
• Handle error/warning/note severity levels
• Integrate with ClangDescriptor using composite pattern
• Add comprehensive unit and integration tests

Resolves JENKINS-76141

Testing Done

Unit Tests

• Created LlvmLinkerParserTest with 7 test methods covering:
  • Basic parsing functionality (4 different severity levels)
  • Versioned LLD linkers (ld.lld-15, ld.lld-18)
  • Mixed output filtering (ignores non-LLD lines)
  • Real-world scenario from JENKINS-76141

Integration Tests

• Added shouldFindAllClangAndLldIssues to ParsersTest
• Validates composite parser functionality (Clang + LLD together)
• All 115 existing parser tests continue to pass

Manual Testing

• Verified Maven build: mvn clean test passes
• Confirmed no regressions in existing functionality
• Tested with sample LLD error output

Verification

• All tests pass locally
• No breaking changes to existing parsers
• Follows established code patterns (based on ClangParser/Gcc4LinkerParser)
• Comprehensive test coverage for new functionality

Submitter Checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[uhafner]

Thanks for your pull request! Just some small comments...

[uhafner]

@sgscheffler ping: I'm not sure if you have enabled your notifications...

[sgscheffler]

Regex now uses named groups (linker, severity, message);
Parser normalizes to basename.
Tests updated to AssertJ idiom and assert the basename.

Author tags fixed;
Explicit severity mapping kept.
All tests pass locally.
Ready for re-review.
@uhafner

[uhafner]

The code looks fine now, thanks!

Can you please have a look at the indention? There are two CheckStyle warnings.