fix(ui): Export FakeEvent for use by UI plugins
fix(ui): Export FakeEvent for use by UI plugins

UI plugins can already dispatch events on the controls, but it is much
less convenient to do so without this export.

Issue #2923

Change-Id: I46edbe01a67e70e052dbbded333af18d086d36ab

shaka-project/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player