[themes] update wear dialog theming

This change specifically restores floating behaviour
and makes wear dialogs fullscreen for
both device default & material

Bug: 228521929
Bug: 273197779
Test: manual
Test: atest android.server.wm.BlurTests
(cherry picked from commit 23458d8bcf66cd620f7325047ecc93be1ac9a4e4)
Change-Id: Iec2bfe491334e29e09a99a3d5ce51d0cfd654a98