Needed design as result of D10875: Spreadsheet: Show data of node.

Issues to be challenged:

• The icon in the header of each node adds unnecessary visual noise
• When zoomed out it's incredibly inconvenient to both activate the toggle as well as see which node is currently being inspected
• Some nodes have multiple geometry output sockets (e.g. Point Separate), as of now there is no way of selecting which output to inspect

Initial proposals:

• Assign shortcut that can be triggered by clicking anywhere on the node (e.g. Ctrl+⇧+LMB)
• Highlight the inspected node in a way that is visually striking

Comments:

• The preview of geometry in the 3D viewport should also be considered to work with this design