Types in `accesskit_consumer` should be renamed

[PoignardAzur]

The core types of accesskit_consumer have poor names:

• Node overlaps with accesskit::Node.
• NodeId overlaps with accesskit::NodeId.
• State is an extremely uninformative name.

I would suggest renaming them:

• Node to NodeRef.
• NodeId to NodeTreeId or FullNodeId.
• State to TreeState.