Cleaned up File menu.

Removed:
 - `New File`,
 - `New Window`.

Closes #1014.

Signed-off-by: Akos Kitta <a.kitta@arduino.cc>

arduino-ide-extension/src/browser/theia/core/common-frontend-contribution.ts

@@ -21,6 +21,7 @@ export class CommonFrontendContribution extends TheiaCommonFrontendContribution
       CommonCommands.TOGGLE_MAXIMIZED,
       CommonCommands.PIN_TAB,
       CommonCommands.UNPIN_TAB,
+      CommonCommands.NEW_FILE,
     ]) {
       commandRegistry.unregisterCommand(command);
     }

arduino-ide-extension/src/browser/theia/core/window-contribution.ts

@@ -0,0 +1,15 @@
+import { injectable } from '@theia/core/shared/inversify';
+import { WindowContribution as TheiaWindowContribution } from '@theia/core/lib/browser/window-contribution';
+
+@injectable()
+export class WindowContribution extends TheiaWindowContribution {
+  override registerCommands(): void {
+    // NOOP
+  }
+  override registerKeybindings(): void {
+    // NOO
+  }
+  override registerMenus(): void {
+    // NOOP;
+  }
+}