Add cache actions and separate binary management to be compatible with caching

[zonorti]

This PR addresses issues #87 #88 #89
I added Cache@v3 action that checks for already downloaded binaries in the cache and reports to the download step if it should download.
If binaries are not cached - download would happen and they would be saved to ${{ runner.temp }}/tailscale_${{inputs.version}}_${{env.TS_ARCH}}/ where cache action would copy from at the end of the workflow in cache post-action.

To try it out one can use uses: zonorti/github-action@github_cache, but beware - it would stop working after this PR is merged and branch is deleted.

All feedback is welcome 👂

[zonorti]

After experimenting with this action more I figured out that it still stays at 10 seconds of runtime, therefore caching makes no sense, unless CDN starts failing again.
I'll close this PR therefore.