Add hardware api for camera, audio input/output selection. (#147)

* chore: Add hardware api for device settings dialog, camera preview, audio input/output selection.

* update.

* update flutter-webrtc.

* chore: add popupmenu for audio/video selection.

* chore: Improve menu tooltip text.

* Removed hardware settings dialog, added it to experimental branch.

* remove unused code.

* Respond to device changes.

* fixed `flutter analyze`.

* update.

* bump verion to v1.1.1.

example/pubspec.lock

@@ -176,7 +176,7 @@ packages:
       name: flutter_webrtc
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.9.3"
+    version: "0.9.4"
   google_fonts:
     dependency: "direct main"
     description: