[Read aloud] Handle Draw tests with the TS text segmentation flag.

This CL:
- Moves two ReadAnythingAppController tests into a new
  ReadAnythingAppControllerV8Segmentation test class. Tests
  in this class will be removed when the TS text segmentation
  flag is enabled everywhere.
- Adds two new TS tests to better test playing from selection
  with the TS text segmentation flag. These tests aren't 100%
  equivalent to the C++ tests, but they test more accurately
  how the TS-based model handles selection.

Future CLs will migrate more of the ReadAnythingAppController
tests into the V8 class and add any missing tests on the TS side.

Bug: 440400392
Change-Id: Ia44d50d8e2107d22b95ffe3de4f07ae9f1360eea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7033421
Commit-Queue: Lauren Winston <lwinston@google.com>
Reviewed-by: Eitan Goldberger <eitang@google.com>
Cr-Commit-Position: refs/heads/main@{#1529060}