Animate icon update from loading state.

Test: manual

Fixing b/129983531. Having app icons pop in without any animation from a solid placeholder color can look janky. Added a sequential fade in, fade out animation.

Preview: https://drive.google.com/file/d/11NgEja7vzm3f3aH3WbEQljUWGKuuK00_/view?usp=sharing
Change-Id: If77e8f480b02d5b7d29f89afa44450c83a68a276