FR: [Crashlytics] Provide linux binaries for `uploads-symbols`

### Feature proposal

* Firebase Component: Crashlytics

Hey!

We're using fastlane for our apps and a lot of its actions can be used on Linux since there are no Mac or iOS specific packages necessary. It also means that we save quite some billable hours since we use a hosted CI solution that bills 10x the amount for every macOS minute spent (GitHub Actions).

Since the `uploads-symbols` binary seems to be closed source (or I didn't find the source), we were wondering if it was at all possible to have an ELF binary or Shell/Python/Ruby/... script of `upload-symbols` to upload dSYMs?

And if not, is there an API endpoint we could manually upload the files to?