Fix flicker when starting folding

The dimensions of LightRevealScrim were used before the view was being measured, causing the entire screen to become black for one frame sometimes (especially after boot.

Now, LightRevealScrim accepts the initial dimensions what are used before the view is measured.

Bug: 261560634
Test: LightRevealScrimTest && many unfolds soon after rebooting
Change-Id: I91d1f2de82c563f085c9565c6e7116abb1e43e1d