Organize command-line options for Supervisor filtering/inheritance

Also have stem process execv() with original command-line arguments so
that they're re-parsed and inherited correctly by supervised-nodes in
the event the stem process needs to be re-created.

scripts/base/frameworks/supervisor/main.zeek

@@ -69,6 +69,11 @@ function Supervisor::restart(nodes: string): bool
 	return Supervisor::__restart(nodes);
 	}
 
+function is_supervisor(): bool
+	{
+	return Supervisor::__is_supervisor();
+	}
+
 function is_supervised(): bool
 	{
 	return Supervisor::__is_supervised();