This PR add several features to release automation:
1. The existing tag-release job has an output that indicates whether the
triggering commit
is a release (i.e. whether it matches the regex)
2. The new followup job runs a new script which fetches the recent
emscripten-releases
revisions, reads the DEPS file from the 'latest' release in
emscripten-releases-tags.json
to find the corresponding emscripten revision and writes it into the
environment
2. The final step reads the emscripten revision from the environment and
creates a
workflow_dispatch event to run the tag-release.yml job on the emscripten
repo
For commits created by the new create-release.yml workflow, we can add
the corresponding release tag. This only runs for changes to the tag
JSON file (and the workflow itself) and only acts on changes created by
the automation (so that it won't interfere if we want to do things
manually).
The action runs the existing create_release.py script in a new mode
created for github actions. Rather than using local git commands, it
uses a public action for creating a PR in the repository. The action can
be triggered from the website or via the CLI tool, for example
gh workflow run create-release.yml -R emscripten-core/emsdk -F
lto-sha=abc123 -F nonlto-sha=234567
