Remove platform_channel_tizen.cc and split its contents into separate files.
Move the PlatformChannel implementation into platform_channel.cc.
Create new files (feedback_manager.h/cc) for FeedbackManager.
Create new files (tizen_shell.h/cc) for TizenShell (previously TizenWindowSystemShell).
Minor refactoring.
Remove the sound_type argument from FeedbackManager.PlaySound and create a new method PlayTapSound.
Let system UI overlay methods (kRestoreSystemUiOverlaysMethod, kSetEnabledSystemUiOverlaysMethod) always return NotImplemented when running on non-common profiles.
platform_channel_tizen.ccand split its contents into separate files.PlatformChannelimplementation intoplatform_channel.cc.feedback_manager.h/cc) forFeedbackManager.tizen_shell.h/cc) forTizenShell(previouslyTizenWindowSystemShell).sound_typeargument fromFeedbackManager.PlaySoundand create a new methodPlayTapSound.kRestoreSystemUiOverlaysMethod,kSetEnabledSystemUiOverlaysMethod) always returnNotImplementedwhen running on non-common profiles.kSetApplicationSwitcherDescriptionMethod,kSetEnabledSystemUIModeMethod,kSetSystemUIOverlayStyleMethod).UI→Ui) for consistency.Contributes to https://github.com/flutter-tizen/engine/issues/239. This change is a continuation of https://github.com/flutter-tizen/engine/pull/248 and https://github.com/flutter-tizen/engine/pull/249.