Fix T95756: Crash inserting geometry node after linking modifier

The root issue was caused by a mistake in modifier copy data which was
wrongly re-generating source modifier data identifier.

The c8cca88851 simply exposed a bug in code which always was there
since the modifiers session UUID was introduced.

Shows an importance of const qualifier :)

source/blender/blenkernel/intern/modifier.c

@@ -391,7 +391,7 @@ void BKE_modifier_copydata_ex(ModifierData *md, ModifierData *target, const int
   }
   else {
     /* In the case copyData made full byte copy force UUID to be re-generated. */
-    BKE_modifier_session_uuid_generate(md);
+    BKE_modifier_session_uuid_generate(target);
   }
 }