Add a content description for the illustration if it is an animation

Since `isAnimatable` is decided in `onBindViewHolder`, we need to register
an onBindListener and update the content description if the current
illustration is an animation.
For the static images, we would like to skip them in Talkback since they
are decorative images.

Bug: 395882764
Test: manually. attach screenshot to the bug
Test: atest ToggleFeaturePreferenceFragmentTest
flag: EXEMPT. bugfix
Change-Id: I57bf96d0891ba553ef29d25ae9489f34b2a832e9