Previously the panel type name of a modifier (e.g. "MOD_PT_Smooth") was
created by copying from the ModifierTypeInfos name.
This meant that modifiers with the same default name would use
the same identifier for the panels.
Since different object types (e.g. OB_GREASE_PENCIL and OB_MESH)
might want to use the same default modifier name, this PR introduces
an idname field in the ModifierTypeInfo struct. This is then used to
generate the panel type name.
For compatibility reasons, the idname is the same as the name for now.
Note: Because the name was used previously, this means that some
modifiers have spaces in their panel type name.
E.g. "MOD_PT_Volume to Mesh".
Pull Request: https://projects.blender.org/blender/blender/pulls/110468
d6aa9906fd