feat(test-validation): add library support

[aliersh]

Description

The test validator was failing for library tests because libraries with internal-only functions have empty ABIs (methodIdentifiers: {}). The validator checks function existence by looking at artifact.Abi.Parsed.Methods, which doesn't work for libraries.

Changes

• Added isLibrary() to detect library artifacts via AST ContractKind
• Added extractFunctionsFromAST() to extract function names from AST nodes
• Modified checkFunctionExists() to use AST for libraries, ABI for contracts
• Added test coverage for the new library validation functions
• Updated exclusions.toml with library-specific exclusions
• Added success message when all validations pass

Fixes #16662

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.72%. Comparing base (2e0d9ab) to head (ab6313b).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #17690      +/-   ##
===========================================
+ Coverage    74.31%   80.72%   +6.41%     
===========================================
  Files          172      117      -55     
  Lines        10955     6170    -4785     
===========================================
- Hits          8141     4981    -3160     
+ Misses        2670     1189    -1481     
+ Partials       144        0     -144     

Flag	Coverage Δ
cannon-go-tests-64	?
contracts-bedrock-tests	80.72% <ø> (ø)

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see 55 files with indirect coverage changes

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