Add dark theme for Shell app.

Bugreport info dialog is used in the BugreportProgressService; services
are not themeable from the manifest file. Added themed context wrapper
in the service file.

Text view underlines are no longer black, and are white in color.

Bug: 128364209
Test: build and flash to device, manually verified the color of the dialog
Change-Id: Ia42c1c7c2b6f2e30d91a5522f1d6b3507b032cdb