Handle any image / label changes for bubble updates in bubble bar

When we get an update to a bubble it could mean that there's a new
message OR that something about the visual representation changed.

This CL modifies BubbleBarController to handle any visual changes
that might have occurred to an updated bubble (e.g. bubble image
changed).

It does this by updating the bubbleInfo on the existing bubble.

Test: manual
Bug: 269670235
Change-Id: I03d2510aef335dafccb32d6adcd4c6adf8b3297d