Use Launcher smartspace instead of SysUI's for the shared element transition.

See justification/explanation in linked bug.

I re-ordered some methods in the unlock controller so they'd make more sense,
they're generally called from top to bottom now during the unlock sequence.

Bug: 229890190
Fixes: 227713319
Test: atest SystemUITests
Test: manual
Change-Id: I58fa437eea183691ff29548143664698498c2105