Restrict and validatee small icon sizes of notifications

This makes StatusBarIconView downscale notification icons if they exceed notification_small_icon_size. This avoids possibility of large memory usage if the app passes a huge drawable asset as the small notification icon.
This restriction currenctly doesn't apply for animated or stateful drawables.

Bug: 209044537
Bug: 193720474

Test: Manually
Change-Id: I1bf19e9d2b1d9fef67e1653e601b11fd74f72e73