[DocsUI Peek] Responsive layout - modal metadata sheet

Add modal metadata sheet for medium layouts. Demo:
http://screencast/cast/NTA0MzMzMzQ3Nzk1NzYzMnw1ODA4YmQyNi1hNA

Bug: 416377167
Flag: com.android.documentsui.flags.use_material3
Flag: com.android.documentsui.flags.use_peek_preview_ro
Test: PeekUiTest#testResponsiveMetadataLayout

Change-Id: I6d88028ba2ef103940667d5379272703bc400804