Deadlock in MockPoolController

[gterzian]

wait_command does a blocking recv_timeout on a std::sync::mpsc::Receiver, which blocks the current thread.

In a single threaded async context(the default for the tokio tests), this means it blocks the thread running the tokio tasks, until the timeout is hit.

The quick fix can be seen in one of the last commits of https://github.com/massalabs/massa/pull/2946

The solution would be to rewrite it with an async channel(where the recv would yield the current task, allowing the other task to actually send the command).

[gterzian]

cc @massalabs/core-team

[AurelienFT]

This doesn't exist anymore in newer version. Close it.