UI Toggle between Classic and Modern (#6763)

* [ENH] Add toggle switch for new MeshCentral UI in settings and top header of the classic UI

* [ENH] Add toggle for new MeshCentral UI in settings and in top headbar of the modern UI

* add showModernUIToggle and store uiviewmode in db

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Co-authored-by: kambereBr <brunokambere@gmail.com>

sample-config-advanced.json

@@ -186,6 +186,7 @@
   "domains": {
     "": {
       "_siteStyle": 2,
+      "_showModernUIToggle": true,
       "title": "MyServer",
       "title2": "Servername",
       "_titlePicture": "title-sample.png",