Take static module capabilities into use

The static module capabilities are now used to query the capabilities of
filters and routers. The new RCAP_TYPE_NOAUTH capability is also taken
into use. These changes removes the need for the `is_internal_service`
function.

examples/testroute.c

@@ -152,7 +152,7 @@ diagnostic(MXS_ROUTER *instance, DCB *dcb)
 
 static uint64_t getCapabilities(MXS_ROUTER* instance)
 {
-    return 0;
+    return RCAP_TYPE_NONE;
 }