- Add storage-repo, storage-repo-branch, and
storage-repo-branch-coverage fields to the actions, to indicate that
the Git filestore should be used.
- The CI provided filestore is still used for crashes and builds.
- Replace generic Filestore.upload_directory with typed upload methods
which matches the download methods.
- Rename upload_latest_build to upload_build to make it more generic.
- Make artifact name prefixes an implementation detail of the store.
For #6052.
Implement filestore based on github actions' artifacts feature.
This uses the github api and the github actions API.
Also fix imports in github_actions_toolkit library that were broken by move to third_party directory.