Add fullscreen client

Added a sample fullscreen client. The client demonstrates usage of the
Wayland Fullscreen Shell protocol.

Does not run without server-side fullscreen shell implementation.

Bug: 896710
Test: Compiled client on ChromeOS and verified it still builds.
Change-Id: I681e864c739faafee07b257fd4c15c49929859cc
Reviewed-on: https://chromium-review.googlesource.com/c/1281424
Commit-Queue: Shawn Gallea <sagallea@google.com>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603146}
8 files changed