feat: make double tap to hold layer optional per key (#662)

* feat: make double tap to hold layer optional per key

* test: fix test serializer

* fix: remove "application start" text

* Add double-tap.svg

* Add closing dot at the end of the sentence.

* fead: add double-tap icon

* Bundle firmware version 8.3.0

* feat: 'layer-double-tap' feature flag

* feat: convert SwitchLayerMode to string enum

package.json

@@ -4,9 +4,9 @@
   "author": "Ultimate Gadget Laboratories",
   "main": "electron/dist/electron-main.js",
   "version": "1.2.2",
-  "firmwareVersion": "8.2.5",
+  "firmwareVersion": "8.3.0",
   "deviceProtocolVersion": "4.3.1",
-  "userConfigVersion": "4.0.1",
+  "userConfigVersion": "4.1.0",
   "hardwareConfigVersion": "1.0.0",
   "description": "Agent is the configuration application of the Ultimate Hacking Keyboard.",
   "repository": {