Adjust the bottom sheet and save UI

1. Add 24dp padding between the title and body.
2. Adjust the padding between body and bottom buttons
3. Modify background of the list view in the bottom sheet.
4. Fix buttons are cut off when there are too many suggestions
   in the bottom sheet.

Bug: 234061218
Bug: 234150685
Test: Manual check the UI for one suggestion, 8 suggestions, light and
dark theme

Change-Id: I6420c24bf9aad8de3bd676a69fd16e79ff598625