feat: go-mod-validator repository/branch exceptions

[erikburt]

Adds optional repo-branch-exceptions input, allowing us to configure exceptions for specific repository+branch combinations.

Changes

• Add repo-branch-exceptions input
  • Add unit tests for parsing logic
• Move validation logic to it's own method, and add support for branch exceptions
• Change general function and type naming to generify to branches rather than default branches explicitly

Testing

Many tests here: https://github.com/smartcontractkit/releng-test/pull/155

Rollout

1. Merge this PR
2. Merge version packages PR
3. Update https://github.com/smartcontractkit/gha-org-workflows/blob/main/.github/workflows/go-mod-validation.yml, adding:

     with:
      repo-branch-exceptions: |
        smartcontractkit/chainlink-ccip:develop

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DX-2402