[MM-55153] Consolidate Desktop App API, use new contextBridge endpoints when available (#25438)

* Create Desktop API module, migrate message passing code

* Changes to use new API

* Use Desktop API to notify when mentions/unreads/expired changes

* Expose Desktop App module to plugins

* Fix lint

* PR feedback

* Fixed an issue where I forgot to check if the method exists first

* Slight API changes

* Fix package

* Convert all to class, add comments, small reworks for PR feedback

webapp/package-lock.json

@@ -60,6 +60,7 @@
         "@mattermost/client": "*",
         "@mattermost/compass-components": "^0.2.12",
         "@mattermost/compass-icons": "0.1.39",
+        "@mattermost/desktop-api": "5.7.0-1",
         "@mattermost/types": "*",
         "@mui/base": "5.0.0-alpha.127",
         "@mui/material": "5.11.16",
@@ -4084,6 +4085,19 @@
       "resolved": "platform/components",
       "link": true
     },
+    "node_modules/@mattermost/desktop-api": {
+      "version": "5.7.0-1",
+      "resolved": "https://registry.npmjs.org/@mattermost/desktop-api/-/desktop-api-5.7.0-1.tgz",
+      "integrity": "sha512-3VdmrdiGwqXpLGomRWiDt8L2LMlOyeAP+S9uKm82JpRt8HoVFeSe9fu39VV9pbnA8O6u6wfnwGUXFeasmmIIkQ==",
+      "peerDependencies": {
+        "typescript": "^4.3"
+      },
+      "peerDependenciesMeta": {
+        "typescript": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/@mattermost/eslint-plugin": {
       "resolved": "platform/eslint-plugin",
       "link": true