app: Add plugin-management and convert to ts

Because there were errors when importing from outside of tree in
the app builds.

This is temporary into a better solution can be done for sharing
this code between headlamp-plugin and app.

Signed-off-by: René Dudfield <renedudfield@microsoft.com>

app/.gitignore

@@ -7,4 +7,5 @@
 /electron/i18n-helper.js
 /electron/preload.js
 /electron/windowSize.js
-electron/windowSize.test.js
+/electron/plugin-management.js
+electron/windowSize.test.js

app/electron/main.ts

@@ -20,8 +20,8 @@ import { userInfo } from 'node:os';
 import path from 'path';
 import url from 'url';
 import yargs from 'yargs';
-import PluginManager from '../../plugins/headlamp-plugin/plugin-management/plugin-management';
 import i18n from './i18next.config';
+import { PluginManager } from './plugin-management';
 import windowSize from './windowSize';
 
 dotenv.config({ path: path.join(process.resourcesPath, '.env') });