LockPatternView dot activation animation.

Animate dot color when it's activated, duration is synchronized with line disappearing animation.
Do not animate dot size if it's not needed.

Bug: 196067470
Bug: 193417780
Tests: Manually
Change-Id: I13fa478f434b2c56a5818a4b639f3e38f7c05c4d
(cherry picked from commit 450633259bc6283f25d98d5e056d39e74bcb8cc7)