[MM-33828] Define CSP for all BrowserWindows, enable contextIsolation for main/settings window, other fixes (#1517)

* [MM-33828] Added CSP to renderer process pages and turned off remote module when not needed

* Turn on contextIsolation and turn off nodeIntegration for main and settings windows

* Check for details.reason instead of object

src/main/views/MattermostView.js

@@ -43,7 +43,7 @@ export class MattermostView extends EventEmitter {
                     `version=${app.version}`,
                     `appName=${app.name}`,
                 ],
-                enableRemoteModule: true,
+                enableRemoteModule: process.env.NODE_ENV === 'test',
                 nodeIntegration: process.env.NODE_ENV === 'test',
             },
             ...options,

src/main/views/webContentEvents.js

@@ -242,8 +242,8 @@ export const addWebContentsEventListeners = (mmview, getServersFunction) => {
 
     listeners[contents.id] = removeListeners;
     contents.once('render-process-gone', (event, details) => {
-        if (details !== 'clean-exit') {
-            log.error(`Renderer process for a webcontent is no longer available: ${details}`);
+        if (details.reason !== 'clean-exit') {
+            log.error('Renderer process for a webcontent is no longer available:', details.reason);
         }
         removeListeners();
     });