UI: support operator enums in Quick Favorites

Part of #59244

This was heavily requested since there are a lot of usages of
`operator_menu_enum` around in our UI [and these menus all cannot be
added to Quick Favorites atm.].

The following are just a small sample from the 3D viewport menus (object
mode), but there are many more.

- Object
-- Set Origin
-- Relations >> Make Local...
-- Convert To
- Add
-- Grease Pencil
-- Empty
-- Force Field
-- Collection Instance
- Select
-- Select All by Type
-- Select Grouped
-- Select Linked
- ...

So in order to make this work, `USER_MENU_TYPE_OPERATOR` /
`bUserMenuItem_Op` is reused (but extended with a string to the property
in question). (Alternatively, a new type could be introduced -- but
would share most of the code with the type that is reused in this
patch).

Depending on being used with an enum or not [detected by the usage of
that new string] we then either call `uiItemFullO_ptr` or
`uiItemMenuEnumFullO_ptr` in `screen_user_menu_draw`.

NOTE: we now also let `uiItemMenuEnumFullO_ptr` take an optional
`wmOperatorCallContext` (would always take the layouts root context
otherwise which is not what we always want for Quick Favorite menus).

NOTE: support for other enums (property enums such as pivot point or
transform orientations) will follow in a separate commit (building upon
6a13b6324b, trying to solve the way these draw as menus)

NOTE: opening User Preferences with such "new" Quick Favorites even
works (just not drawn with a menu)

@@ -612,6 +612,7 @@ struct bUserMenu *ED_screen_user_menu_ensure(struct bContext *C);
 struct bUserMenuItem_Op *ED_screen_user_menu_item_find_operator(struct ListBase *lb,
                                                                 const struct wmOperatorType *ot,
                                                                 struct IDProperty *prop,
+                                                                const char *op_prop_enum,

@@ -2896,6 +2896,7 @@ void uiItemMenuEnumFullO_ptr(uiLayout *layout,
                              const char *propname,
                              const char *name,
                              int icon,
+                             wmOperatorCallContext *opcontext,

@@ -3555,6 +3555,7 @@ void uiItemMenuEnumFullO_ptr(uiLayout *layout,
                              const char *propname,
                              const char *name,
                              int icon,
+                             wmOperatorCallContext *opcontext,

@@ -199,2 +206,3 @@
-static void screen_user_menu_draw(const bContext *C, Menu *menu)
+static void screen_user_menu_draw(const bContext *C_const, Menu *menu)
 {
+  bContext *C = (bContext *)C_const;

@@ -228,0 +237,4 @@
+          }
+          else {
+            uiItemMenuEnumFullO_ptr(menu->layout,
+                                    C,