[DocsUI M3] Uplift File list row colors/states

* Remove hover/ripple for file list row.
* Update bg colors for selected/unselected states, add
  round corner.
* Update colors for the text/icons.

Check the bug item for the demo.

Bug: 381960982
Test: Manual inspection
Flag: com.android.documentsui.flags.use_material3
Change-Id: I19300a16c6d7ff73be08985948a55b4f94259bae