[Property Editor] Tests to make sure our constants are in-sync with those in the analysis_server

DevTools relies on keeping some of our constant values in sync with those in the `analysis_server`:

See for example:
* https://github.com/flutter/devtools/blob/ee87359095a5c1a832fdd8084098206f44d4b733/packages/devtools_app/lib/src/shared/editor/api_classes.dart#L30
* https://github.com/flutter/devtools/pull/8818#discussion_r1934170082

This could be accomplished by fetching the raw contents of the file from the Dart SDK repo on Github. However, I believe the requests will be rate-limited to 60/hour unless we authenticate with a Github token.

* https://docs.github.com/en/rest/repos/contents?apiVersion=2022-11-28
* https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api?apiVersion=2022-11-28#primary-rate-limit-for-unauthenticated-users

We should either 1) create a Github token secret we can use for these tests 2) schedule the tests to only run daily so as not to exceed the rate limit