[New Feature]: Postpone Validation until CLA is signed

### Description of the new feature/enhancement

Some users have not signed the CLA but raised multiple PRs that either fail validation or get closed. To ensure validation infrastructure time is best utilized, it would be ideal if the validation could be postponed until the CLA is agreed to unless manually run by `@wingetbot run`

### Proposed technical implementation details (optional)

_No response_

No files or tests are named. Start by tracing the validation infrastructure and CLA-signing check, then compare the normal trigger with the manual `@wingetbot run` path; done means unsigned-CLA PRs are postponed while manual runs still validate.

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