[studio/modlib] Add variant of ComboBox that takes callback

src/olympic/studio/modlib/include/studio/imguiutil.hpp

@@ -148,6 +148,19 @@ bool BeginPopup(turbine::Context &ctx, ox::CStringView popupName, bool &show, Im
  */
 bool ComboBox(ox::CStringView lbl, ox::SpanView<ox::String> list, size_t &selectedIdx) noexcept;
 
+/**
+ *
+ * @param lbl
+ * @param callback
+ * @param selectedIdx
+ * @return true if new value selected, false otherwise
+ */
+bool ComboBox(
+		ox::CStringView lbl,
+		std::function<ox::CStringView(size_t)> const&f,
+		size_t strCnt,
+		size_t &selectedIdx) noexcept;
+
 bool FileComboBox(
 		ox::CStringView lbl,
 		studio::StudioContext &sctx,