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

[elliette]

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

See for example:

• devtools/packages/devtools_app/lib/src/shared/editor/api_classes.dart

  Line 30 in ee87359

  enum LspMethod {

• [Property Editor] Handle errors from the Analysis Server #8818 (comment)

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