[Media TTT] Refactor the command line interface into its own class and

use sealed classes for the chip states.

The sealed class doesn't do anything in this CL, but it will become
useful in future CLs.

Sample command: adb shell cmd statusbar media-ttt-chip-add Tablet TransferInitiated

Bug: 203800327
Test: MediaTttCommandLineHelperTest, MediaTttChipControllerTest
Test: Re-tested adb commands and they still trigger the correct UIs
Change-Id: Iffd53c5648dac0307d282158122365613fb7b653