Add TV specific TvUsbConfirmActivity and TvUsbPermissionActivity.

The new activities are based on the TvBottomSheetActivity and do not
show the "always use" checkbox because we did not find any strong use
case for it.
Extracted common logic into UsbDialogHelper which can be used also for
non-TV counterparts.

Bug: 196780010
Test: Open camera app that requests access to USB camera. Verify that TvUsbPermissionActivity is shown and verify functionality.
Test: Have an app installed which registers for USB_DEVICE_ATTACHED broadcast in its AndroidManifest. Attach USB camera device and verify that TvUsbConfirmActivity is shown and verify functionality.
Change-Id: Ib100e117ea0ea12adbca1c56e4ec8fc3d0bfc52f