Can check if the current window is the first one.

Closes #1070

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

arduino-ide-extension/src/electron-common/electron-main-window-service-ext.ts

@@ -0,0 +1,7 @@
+export const electronMainWindowServiceExtPath = '/services/electron-window-ext';
+export const ElectronMainWindowServiceExt = Symbol(
+  'ElectronMainWindowServiceExt'
+);
+export interface ElectronMainWindowServiceExt {
+  isFirstWindow(windowId: number): Promise<boolean>;
+}