GitHub App: fix PR builds and import

[stsewd]

• Update admin to make it more usable for remote repos/orgs
• When implementing the signature of the base service class I forgot to return a tuple, the tuple contains a boolean and the response, which is weird, because all other method return only a boolean, and we never use the response. So I went ahead and removed the need to return a tuple from all services.
• Allow activating PR previews for projects connected to a GH app from the form.
• Build from PRs for projects that explicitly have the option enabled, since now with the GH app we always listen to all events.
• Tests tests tests

[Copilot]

Pull Request Overview

This PR streamlines webhook service methods by eliminating tuple returns in favor of simple boolean values, while also introducing GitHub App integration support and updating related tests and admin configurations.

• Remove tuple returns from webhook service methods.
• Introduce GitHub App integration tests and update existing tests accordingly.
• Update admin and view logic to conditionally enable external builds based on integration type.

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
readthedocs/rtd_tests/tests/test_oauth.py	Updated tests to consume a boolean return from webhook setup and update methods.
readthedocs/rtd_tests/tests/test_celery.py	Added tests for GitHub App service build status callback handling.
readthedocs/projects/tests/test_views.py	Introduced tests for GitHub App integration and external build option behavior.
readthedocs/projects/forms.py	Modified form validation logic for external builds when using a GitHub App integration.
readthedocs/oauth/views.py	Filtered projects by external_builds_enabled in webhook event handling.
readthedocs/oauth/utils.py	Adjusted webhook update logic to reflect new boolean return type.
readthedocs/oauth/tests/test_githubapp_webhook.py	Expanded GitHub App webhook tests for various PR event scenarios.
readthedocs/oauth/tasks.py	Updated webhook setup tasks to expect boolean returns.
readthedocs/oauth/services/gitlab.py	Refactored webhook methods with type hints and simplified boolean returns.
readthedocs/oauth/services/githubapp.py	Updated webhook service methods with GitHub App integration to return a boolean.
readthedocs/oauth/services/github.py	Modified webhook methods to remove tuple returns and include type hints.
readthedocs/oauth/services/bitbucket.py	Adapted webhook methods to use simple boolean returns and updated docstrings.
readthedocs/oauth/services/base.py	Documented base service methods to reflect the new return type signature.
readthedocs/oauth/admin.py	Enhanced admin configuration to support GitHub App installations.

[humitos]

Good work! 🧑‍🏭

[humitos]

Isn't it possible to use the following and avoid having to define the method below?

Suggested change

	"vcs_provider",
	"remote_repository__vcs_provider",

[stsewd]

nope :/ django doesn't like it, or at least in 4.2, I see that 5.2 has that case as a valid example https://docs.djangoproject.com/en/5.2/ref/contrib/admin/#django.contrib.admin.ModelAdmin.list_display

[humitos]

Same here.