[flexiglass] Introduces use of alignment lines.

Alignment lines are used to communicate the position of the lock icon
and for new custom layout logic in both the default and shortcuts-beside-UDFPS
blueprints to avoid placing other elements on top of the lock icon.

This acts as a proof of concept, proving that we could also use
alignment lines from the clock section to communicate the same such that
blueprints can place elements above, below, or around various clock
elements (some clocks, like the weather clock, use multiple clock
elements and need other lockscreen elements to not overlap them).

Bug: 316211368
Test: manually verified on both blueprints
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT
Change-Id: Ic014e30e8b354b1952992f67f091d4da20c61923