EMQX-9021

[ieQu1]

Fix problem when running mria:join(Node), mria:leave(), mria:join(Node) sequence of actions on the replicant node.

Oftentimes it leads to hangup of the start callback. I've identified two reasons for this behavior:

• Mria application restarts for both join and leave. I didn't take into account that OTP's application_master module kills all processes with the group leader matching the pid of the master process of the stopped app. It includes optvar "waker" processes, when they are started from inside mria supervision tree. Prior to ver. 1.0.4 optvar library couldn't handle crashes of the waker processes, and never unblocked the readers.
• Start callback may involve calls to the application controller. When the replicant leaves the cluster, all tables are blocked until it connects to another core node. It means applications that wait for table can block application controller, and the next invocation of the start callback cannot succeed.

[ieQu1]

Depends on #131