refactor: improve device interface types (#996)

app/assets/javascripts/Device/DesktopDeviceInterface.ts

@@ -0,0 +1,11 @@
+import { DeviceInterface, Environment } from '@standardnotes/snjs'
+import { WebOrDesktopDevice } from '@/Device/WebOrDesktopDevice'
+import { WebCommunicationReceiver } from './DesktopWebCommunication'
+
+export function isDesktopDevice(x: DeviceInterface): x is DesktopDeviceInterface {
+  return x.environment === Environment.Desktop
+}
+
+export interface DesktopDeviceInterface extends WebOrDesktopDevice, WebCommunicationReceiver {
+  environment: Environment.Desktop
+}