PyAPI: support accessing the original value for RNA enum parsing

Needed in siturations when the input argument is needed for exception messages.

source/blender/python/intern/bpy_rna.c

@@ -832,6 +832,8 @@ int pyrna_enum_value_parse_string(PyObject *o, void *p)
           parse_data->items, identifier, &parse_data->value, "enum identifier") == -1) {
     return 0;
   }
+
+  parse_data->value_orig = o;
   parse_data->is_set = true;
   return 1;
 }
@@ -851,6 +853,7 @@ int pyrna_enum_bitfield_parse_set(PyObject *o, void *p)
           parse_data->items, o, &parse_data->value, "enum identifier set") == -1) {
     return 0;
   }
+  parse_data->value_orig = o;
   parse_data->is_set = true;
   return 1;
 }

source/blender/python/intern/bpy_rna.h

@@ -219,6 +219,13 @@ int pyrna_set_to_enum_bitfield(const struct EnumPropertyItem *items,
  */
 struct BPy_EnumProperty_Parse {
   const EnumPropertyItem *items;
+  /**
+   * Set when the value was successfully parsed.
+   * Useful if the input ever needs to be included in an error message.
+   * (if the value is not supported under certain conditions).
+   */
+  PyObject *value_orig;
+
   int value;
   bool is_set;
 };