Remove uuidtools while maintaining validation logic

[AlexMooney]

What does this PR do?

Remove the dependency on the uuidtools gem in favor of a couple of lines of plain old Ruby.

In #2216:

since uuidtools has not been updated in 5 years. It seems most likely the fix would be using something from Ruby's standard library to replace the functionality.

Additional Notes

It seems that the only use for this gem is validating UUID input.

• Implementation of UUIDTools::UUID.parse
  • I kept the two failure cases (not a string & not a uuid) identical to the gem.
• Implementation of UUIDTools::UUID.to_s
  • These are the only methods being used, but .parse.to_s should be the same as the original data, aside from the validation!
• Ruby 3.4's test_uuid is the source of the regexp I used to replace UUIDTools.

Review checklist

Please check relevant items below:

• This PR includes all newly recorded cassettes for any modified tests.
  • No need
• This PR does not rely on API client schema changes.
  • The CI should be fully passing. TBD!
• Or, this PR relies on API schema changes and this is a Draft PR to include tests for that new functionality.
  • Note: CI shouldn't be run on this Draft PR, as its expected to fail without the corresponding schema changes.

[buraizu]

No docs review needed