Reorder the context menu and add divider

The old order is the same to ActionMode but it would be better to
reoredr the items for ContextMenu to be same with desktop UI.
Also, add divider between undo/redo and clipboard menus, and others.

The old order was

 Undo
 Redo
 Cut
 Copy
 Paste
 Share
 Select All
 Autofill
 Paste as plain text

The new order is

 Undo
 Redo
 --------------------
 Cut
 Copy
 Paste
 Paste as plain text
 Select All
 --------------------
 Share
 Autofill

Bug: 240385199
Test: Manually done
Change-Id: Icae50f8b12467953b4ce3a3fbc1fa7605e769035