GODT-1431 Prevent watcher when not using disk on cache

- change: Rename Cacher -> MsgCachePool
- change: Do not run watcher when using memory cache
- add: Allow to cancel cacher jobs (added context)
- change: Fix behavior on context cancel (was causing no internet)

internal/users/user.go

@@ -120,7 +120,6 @@ func (u *User) connect(client pmapi.Client, creds *credentials.Credentials) erro
 			return err
 		}
 
-		// NOTE(GODT-1158): If using in-memory cache we probably shouldn't start the watcher?
 		u.store.StartWatcher()
 	}