MEDIUM: mworker: each worker socketpair is a CLI listener

The init code of the mworker_proc structs has been moved before the
init of the listeners.

Each socketpair is now connected to a CLI within the workers, which
allows the master to access their CLI.

The inherited flag of the worker side socketpair is removed so the
socket can be closed in the master.
diff --git a/include/proto/cli.h b/include/proto/cli.h
index da80af7..de1305b 100644
--- a/include/proto/cli.h
+++ b/include/proto/cli.h
@@ -28,5 +28,7 @@
 
 int cli_has_level(struct appctx *appctx, int level);
 
+int mworker_cli_sockpair_new(struct mworker_proc *mworker_proc, int proc);
+
 #endif /* _PROTO_CLI_H */