[MM-59823] Migrate BrowserView to WebContentsView (#3177)

* Migrate to WebContentsView from BrowserView

* A bit of cleanup, stop holding reference to the loading screen

* Fix tests

* Fix i18n

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Co-authored-by: Mattermost Build <build@mattermost.com>

package.json

@@ -165,7 +165,7 @@
     "bootstrap": "4.6.1",
     "bootstrap-dark": "1.0.3",
     "classnames": "2.5.1",
-    "electron-context-menu": "3.6.1",
+    "electron-context-menu": "4.0.4",
     "electron-extension-installer": "1.2.0",
     "electron-is-dev": "2.0.0",
     "electron-log": "5.2.0",