[flexiglass] Pattern bouncer UX polish.

- Adds haptic feedback when a dot is selected.
- Fixed issue where lines were not fading out.
- Makes line fade-out animation match legacy code.
- Adds interpolation of the line start position as the line fade out.

Bug: 281871687
Test: Manual verification. Please see video capture attached to
b/281871687.

Change-Id: Ic37a9c5fea3b95f28d38f9d20d0437977b11a398