Add theme settings for Data Type color in Nodetree

Data type color in Nodetree Sockets and Connections is hardwired. It would be good to have theme setting for it:

The current saturated colors brings a challenge when creating a well-balanced low saturation theme.

Themes have setting for different types of Nodes; Group, Ceometry, Converter, ....

For consistency, data type colors should also have Theme settings, as those colors appear in same context, and changing the other changes the balance between them.

Also, some backgrounds may render the default colors hard to see, restricting the colors we can use in a theme.

Most, if not all, similar elements in UI has a color settings in the Themes, for example :

• Axis&Gizmos
• Icon Colors
• Curve Handle Type colors
• Frame/Keyframe type colors
• Collection Colors
• and more...

I don't see any reason why Data Type Color shouldn't have theme setting, as now it is inconsistent with other stuff in Blender.