feat: validate-pr workflow now enforces proper commit formatting @W-23251216@

[jfeingold35]

Previously, the validate-pr workflow only checked that a Pull Request's title and body both contained a string that looked like it could conceivably be a GUS work item (i.e., W-\d{7,8} in title, and @W-\d{7,8}@ in body).

Now, the workflow enforces multiple things:

1. The Title matches the following format: <type> (<optional-scope>): <description> (W-XXXXXXX)
   where <type> is one of: feat|fix|docs|style|refactor|perf|test|build|ci|chore|revert
2. The Body contains the same work item from the Title, wrapped in @'s.
3. If these criteria are violated, a pretty little criteria tree is logged with checks and x's to show what you did wrong.

This enhancement was done for @W-23251216@.

(all of the testing I did against this was done using this PR in testPackageRelease, and you can check the action execution history here to see me finally get to ones that work properly.