Android: Make androidx.window.extensions library available

This does not yet add it to chrome.

Bug: 1415351
Change-Id: Ie4075e9e0f9ffc7d89fe60950c01b45b69552f46
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5148729
Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1242020}
NOKEYCHECK=True
GitOrigin-RevId: 70a1f51e438fd782bedac6fd76193270638678f4