Adds a new overlay called "Timings" to the Geometry Node editor.
This shows the node execution time in milliseconds above the node.
For group nodes and frames, the total time for all nodes inside
(recursively) is shown. Group output node shows the node tree total.
The code is prepared for easily adding new rows of information
to the box above the node in the future.
Differential Revision: https://developer.blender.org/D13256
Now that `node_intern.hh` is a C++ header, we can use C++ types
there. This patch replaces the linked list of dragged links with a
vector. Also, the list of drag operator custom data, `nldrag`, doesn't
seem to need to be a list at all, so I just made it a unique pointer.
Differential Revision: https://developer.blender.org/D13252
Erik Abrahamsson
Hans Goudey