Blender Git Loki

UI: support Copy To Selected for id-properties [GN modifier properties]

Both {key Alt} editing behavior as well as `Copy To Selected` were not
working on geometry nodes modifiers (even if these matched exactly -
having the same nodegroup - on multiple objects)

Reason is that code checks pointer equality on the discovered properties
[geometry nodes modifier properties are stored as ID properties], but
these are not the same across objects (since these are fetched from
NodesModifierSettings - which are different on different objects).

note: if general custom properties are "API defined" on existing classes,
this was working, we are getting the exact property for different IDs in
this case

Now be more permissive with ID properties not defined on classes in
general and dont check pointer equality for them. For ID properties on
specific IDs (not the ones defined on classes) this //might// be undesired
(havent spotted issues though, even if equally named ID properies with
different types existed -- this then simply does nothing).

For geometry nodes modifiers, new code also checks if the nodegroups are
the same [since generic naming "Input_XXX" is shared for all modifiers --
and starting to copy over things to unrelated modifiers is not desired
here].

Fixes T93983.

Maniphest Tasks: T93983

Differential Revision: https://developer.blender.org/D13573