Change color of the tab underline to match the UX mocks.

Even though the color can be changed by updating
Theme.DeviceDefault.ResolverCommon's colorControlActivated,
that also changes the background color when selecting a
list item in the resolver list. Instead, we change only
the tab-specific styling.

Fixes: 149085716
Test: manual
Change-Id: I9c3399828048ffe71db5e15d09c5cad1fd205d0d