Fix for missing widgets

This works around around a Jetpack Compose bug where if we add a child
to the element inside an AndroidView composable before the element has
been laid out, it will fail to render. We therefore delay processing the
RemoteViews for the widget until after the parent has been laid out.

Test: manually on device by verifying widgets properly show up
Flag: EXEMPT bugfix
Bug: 387938328
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:9c4b228662a1881efdd42e8f2fac3f50899c311f)
Merged-In: I3b094086dd133981c37fa9709547334091fcb580
Change-Id: I3b094086dd133981c37fa9709547334091fcb580