chore: refactor browser IPC into TS and app API into TS (#16921)

* chore: refactor browser IPC into typescript

* chore: refactor app.ts into Typescript

* Refactors app.dock into cpp
* Removes app.launcher which has not existed for 3 years
* Removes 2 deprecated APIs (that have been deprecated for more than one
major)
* Refactors deprecate.ts as well

lib/browser/api/app.ts

@@ -0,0 +1,68 @@
+import * as path from 'path'
+
+import * as electron from 'electron'
+import { EventEmitter } from 'events'
+
+const bindings = process.atomBinding('app')
+const commandLine = process.atomBinding('command_line')
+const { app, App } = bindings
+
+// Only one app object permitted.
+export default app
+
+const { deprecate, Menu } = electron
+
+let dockMenu: Electron.Menu | null = null
+
+// App is an EventEmitter.
+Object.setPrototypeOf(App.prototype, EventEmitter.prototype)
+EventEmitter.call(app as any)
+
+Object.assign(app, {
+  setApplicationMenu (menu: Electron.Menu | null) {
+    return Menu.setApplicationMenu(menu)
+  },
+  getApplicationMenu () {
+    return Menu.getApplicationMenu()
+  },
+  commandLine: {
+    hasSwitch: (theSwitch: string) => commandLine.hasSwitch(String(theSwitch)),
+    getSwitchValue: (theSwitch: string) => commandLine.getSwitchValue(String(theSwitch)),
+    appendSwitch: (theSwitch: string, value?: string) => commandLine.appendSwitch(String(theSwitch), typeof value === 'undefined' ? value : String(value)),
+    appendArgument: (arg: string) => commandLine.appendArgument(String(arg))
+  } as Electron.CommandLine,
+  enableMixedSandbox () {
+    deprecate.log(`'enableMixedSandbox' is deprecated. Mixed-sandbox mode is now enabled by default. You can safely remove the call to enableMixedSandbox().`)
+  }
+})
+
+app.getFileIcon = deprecate.promisify(app.getFileIcon)
+
+app.isPackaged = (() => {
+  const execFile = path.basename(process.execPath).toLowerCase()
+  if (process.platform === 'win32') {
+    return execFile !== 'electron.exe'
+  }
+  return execFile !== 'electron'
+})()
+
+if (process.platform === 'darwin') {
+  const setDockMenu = app.dock.setMenu
+  app.dock.setMenu = (menu) => {
+    dockMenu = menu
+    setDockMenu(menu)
+  }
+  app.dock.getMenu = () => dockMenu
+}
+
+// Routes the events to webContents.
+const events = ['login', 'certificate-error', 'select-client-certificate']
+for (const name of events) {
+  app.on(name as 'login', (event, webContents, ...args: any[]) => {
+    webContents.emit(name, event, ...args)
+  })
+}
+
+// Wrappers for native classes.
+const { DownloadItem } = process.atomBinding('download_item')
+Object.setPrototypeOf(DownloadItem.prototype, EventEmitter.prototype)