[TypeSpec Requirement] Add date-based suppression expiration mechanism

[mikeharder]

- tool: TypeSpecRequirement
  path: data-plane/**/*.json
  reason: Schedule fully committed until this date
  validThrough: 2024-05-31

• If currentDate <= validThrough, apply suppression
• If currentDate > validThrough, print warning and ignore suppression
• Should validThrough be required or optional?
• If required, should we enforce a maximum range (e.g. 1 year from currentDate)?

[konrad-jamrozik]

This builds on:

• [TypeSpec Requirement] Add suppression mechanism #27348

[rkmanda]

We dont foresee any permanent suppressions for the TypeSpec requirement. So we should make validThrough required and the max range could be 6 months from currentDate

[mikeharder]

Closing in favor of #28754