Introduce TextLine#measureAllbounds

This new method computes the horizontal character bounds by making
use of the character advances returned from native layer. It'll be
used in TextView to populate character bounds, and it's much efficent
compared to calling getPrimaryHorizontal for each character.

Bug: 233922052
Test: atest android.text.TextLineTest
Change-Id: Icdd53e61e2d1513b2231affb19bb00ea5d938d48