[MM-36421] Replace server tabs with dropdown menu (#1647)

* WIP

* WIP

* PoC for dropdown - logic stuff

* Most of the logic for the dropdown

* Working dropdown menu to pick servers

* Mentions, unreads and expired working. Many styles are working.

* Some more styles

* Dark mode and other stuff

* Some cleanup

* Generate build

* PR feedback

* More PR feedback

src/main/views/MattermostView.ts

@@ -73,19 +73,17 @@ export class MattermostView extends EventEmitter {
         this.window = win;
 
         const preload = getLocalPreload('preload.js');
-        this.options = {
-            webPreferences: {
-                contextIsolation: process.env.NODE_ENV !== 'test',
-                preload,
-                additionalArguments: [
-                    `version=${app.getVersion()}`,
-                    `appName=${app.name}`,
-                ],
-                enableRemoteModule: process.env.NODE_ENV === 'test',
-                nodeIntegration: process.env.NODE_ENV === 'test',
-                ...options.webPreferences,
-            },
-            ...options,
+        this.options = Object.assign({}, options);
+        this.options.webPreferences = {
+            contextIsolation: process.env.NODE_ENV !== 'test',
+            preload,
+            additionalArguments: [
+                `version=${app.getVersion()}`,
+                `appName=${app.name}`,
+            ],
+            enableRemoteModule: process.env.NODE_ENV === 'test',
+            nodeIntegration: process.env.NODE_ENV === 'test',
+            ...options.webPreferences,
         };
         this.isVisible = false;
         this.view = new BrowserView(this.options);