Streamline API calls from UI (incl. Fix #1311, #1314) (#1312)

* JSONeditor: Disable watchers when updating selections dynamically

* Refactor - Load last instance config when loading UI page

* LED Devices - Notify getproperties watchers for configured hostname

* Remove unused variable

* Fix #1314 - Additional classic & matrix configuration items were not saved

.vs/launch.vs.json

@@ -9,7 +9,8 @@
       "name": "Run hyperion with debug option and external console",
       "args": [
         "-d",
-        "-c"
+        "-c",
+        "-u test"
       ],
       "externalConsole": true
     }