Adding unit tests

Tests that the screen record tile on/off/cancel works as expected and that the
recording controller updates state and calls listeners correctly

Also updated a couple methods so they make more sense (aren't called
multiple times per event, differentiating between onRecordingEnd and
onCountdownEnd)

Test: atest ScreenRecordTileTest RecordingControllerTest
Bug: 144944929
Change-Id: Ic2d44bbc250bcb1e90eff78839c9ab37c0d93564