feat: Support atomic replica takeover (#1314)

* fix(server): Initialize ServerFamily with all listeners.

- Add a test for CLIENT LIST which is the visible result of this.

* use std move

* feat: Implement replicas take over

* Basic test

* Address CR comments

* Write a better test. Sadly it fails

* chore: Expose AwaitDispatches for reuse in takeover

* Ensure that no commands can execute during or after a takeover

* CR progress

* Actually disable the expiration

* Improve tests coverage

* Fix the dispatch waiting code

* Improve testing coverage and fix a shutdown snaphot bug

* don't replicate a replica

src/server/common.h

@@ -134,6 +134,7 @@ enum class GlobalState : uint8_t {
   LOADING,
   SAVING,
   SHUTTING_DOWN,
+  TAKEN_OVER,
 };
 
 enum class TimeUnit : uint8_t { SEC, MSEC };