This PR
- adds the `cache-server` command so act_runner can run as a cache server. When running as a cache server, act_runner only processes the requests related to cache and does not run jobs.
- adds the `external_server` configuration for cache. If specified, act_runner will use this URL as the ACTIONS_CACHE_URL instead of starting a cache server itself.
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/275
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-committed-by: Zettat123 <zettat123@gmail.com>
Zettat123