Use DeviceProfile.widthPx to initialize Taskbar touchableRegion

- TaskbarDraglayer.width isn't initialize when Taskbar is recreated before layout, so use DeviceProfile.widthPx instead
- Also listen for DeviceProfile change in TaskbarInsetsController to update Taskbar touchableRegion

Fix: 233316713
Test: Switch to 3 button, nav button works. Swtich to gesture nav, taskbar icon can be tapped
Test: Rotate deice, whole Taskbar should still be touchable
Change-Id: I29ff86fd8616a620f98d9b5438cc586bd69fac33