Display WearBugreportWarningActivity on Wear after bugreport is done

Display WearBugreportWarningActivity as the bug report warning dialog
after bugreport is done on Wear. WearBugreportWarningActivity is defined
in ClockworkShell.

Bug: 190226948

Test: manual test
Take bugreport on Wear, verify that WearBugreportWarningActivity can
be displayed when user choose to display warning dialog:
screenshot.googleplex.com/4udFJuu6M9JmXE4,
screenshot.googleplex.com/4GFT9G5EMHMkwVm

also verify that no warning dialog will be displayed on future
bugreports when user choose "Don't show again" from warning dialog
https://screenshot.googleplex.com/BzyxTJ8siUTA6Xs

(cherry picked from commit 0402d0b12d61f72ee8628b6ef9efad4e74e18fcd)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:470cbee933a650ec239f9300bdcbe95f8f3fe874)
Merged-In: I81cfae4e79f0904b6ca18889fcca65b647c3db4b
Change-Id: I81cfae4e79f0904b6ca18889fcca65b647c3db4b