[Read Aloud] Automatically switch to language when voice selected.

This allows us to play with non-high quality voices in the correct
locale before the high quality voices download.

Bug: 345722763
Change-Id: Id7745640ce7ba0f07da2e3f3706f1d0743025865
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5609515


Reviewed-by: Eitan Goldberger <eitang@google.com>
Commit-Queue: Lauren Winston <lwinston@google.com>
Cr-Commit-Position: refs/heads/main@{#1312814}