[DocsUI M3] Restyle the snackbar

Override the default style by adjusting the margin and max width.

Check the attached bug for the demo.

Bug: 433352372
Test: m DocumentsUIGoogle && manual inspect
Flag: com.android.documentsui.flags.use_material3
Change-Id: I0d88672a47706681c54f53d5c9acec65f6df4b68