[minor] REST API server not starting automatically on StreamGrid restart

[SR-G]

Tested with 2.0.0 and 3.0.0, a very small bug :

• when the REST API is activated, if StreamGrid is restarted
• then once restarted, in the settings, one can see the REST API in the previous state ("Enabled") but at the same time, the server is not running / not started.
• then it's needed to disable/enable it manually, for the server to be restarted

I think that :

• if the REST API is disabled, it should not be started (nothing to do)
• but if it's activated, then it should be automatically started when StreamGrid is (re)launched