feat: support offline mode (#2128)

* Add: Actions Offline Mode

* Add: Actions Offline Mode

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/runner/runner.go

@@ -23,6 +23,7 @@ type Config struct {
 	Actor                              string                       // the user that triggered the event
 	Workdir                            string                       // path to working directory
 	ActionCacheDir                     string                       // path used for caching action contents
+	ActionOfflineMode                  bool                         // when offline, use caching action contents
 	BindWorkdir                        bool                         // bind the workdir to the job container
 	EventName                          string                       // name of event to run
 	EventPath                          string                       // path to JSON file to use for event.json in containers