[EngSys] ModelValidation, SemanticValidation, and BreakingChanges should ignore common-types

[mikeharder]

PR: #33043

Checks ModelValidation, SemanticValidation, and BreakingChanges are all failing, because they consider the changes to specification/common-types as "spec changes" and try to validate the files, which always fails since they're aren't complete specs.

Fix is to exclude /specification/common-types/** and /*.json (json files in repo root) when detecting spec files to analyze.