cursor shape issues

The cursor shape protocol is following the css ui spec for the allowed cursor values.

Unfortunately, the css ui spec is a bit insufficient when it comes to cursor values.

There are at least two problems that should be addressed before hardcoding these cursor values into a Wayland protocol.

• The 'move' cursor is meant to represent that the move action is selected during a dnd operation (that is why it is in the "Drag and Drop" section of the css spec), but since there is no cursor for moving things in the "Resizing and scrolling" section, everybody is misusing 'move' for moving windows, and similar operations that are not related to dnd actions. Suggestion: Add a 'nesw_move' value that can be used instead of 'move' for these cases.
• The Wayland protocol supports 'ask' as a dnd action, and cursor themes commonly include a dnd-ask cursor. But the css spec omitted this drag action from their cursor enumeration. It should be added, to fully support Wayland dnd in the cursor shape protocol.