MediaRouterV2: MediaRouteChooserDialog layout

- Change the title to "Cast to".
- Remove the cast icon on the title.
- Add a default image icon for route items.
- Tweak the paddings, margins and sizes of the route item.

TODOs
- Need to change the image icon once we get the images from UX.
- Adjust the text style.
- Test and apply the new ux for before v7.

Bug: 23117157
Change-Id: I485730b14dfd2fe00bfd6753d27314522582d606
6 files changed