Test QSTileViewModelImpl

Renamed the class because we now consider QSTileViewModelImpl to be the
only implementation of the interface.

The tests use QSTileViewModel interface to invode methods, which makes
them easily expandable to cover other implementations if needed.

Test: atest QSTileViewModelTest
Test: atest QSTileViewModelUserInputTest
Fixes: 299908635
Flag: LEGACY QS_PIPELINE_NEW_TILES DISABLED
Change-Id: I2d12ce3fa06d78be3e74654a1ba896fff89bb7d2