Apply size limit and measurement logic to navpill

NavPill should have at most 247dp, and attribution should be at most 37%
the size of the container.

Test: visual
Test: atest NavBarPillScreenshotTest
Bug: 407662106
Flag: com.android.systemui.enable_underlay
Change-Id: I00ddecf597b87977aee324fdc01bb7a76f8de281