Add CTS test for underlines not affecting width

We measure some text with and without an UnderlineSpan with a
boundary where the text would be kerned. The widths should be the
same.

Bug: 32907446
Test: cts-tradefed run cts-dev --module CtsTextTestCases
Change-Id: Ib0cfeeb72cc45c3bb44ccc29327f590ab62e387a
1 file changed