Translate TextView content description if exist

Screen reader(Talkback) will read content description first if the
developers set. We only translate TextView text, this may cause the
screen reader will not read the translated text if the developers set
content description.

To fix the issue, we also send the content description to translate.
When the translated text is shown, we also set content description
with translated content description and reset to original content
description if show original text.

Bug: 187134784
Test: atest CtsTranslationTestCases
Change-Id: I6986384260627a0539780b7293d47666c442d852