Cleanup: Pass StringRef instead of const std::string &

No need to construct a std::string unless we're going to move from it.

source/blender/editors/include/UI_interface.hh

@@ -297,7 +297,7 @@ blender::ui::AbstractTreeView *UI_block_add_view(
     std::unique_ptr<blender::ui::AbstractTreeView> tree_view);
 
 void UI_alert(bContext *C,
-              const std::string &title,
-              const std::string &message,
+              blender::StringRef title,
+              blender::StringRef message,
               eAlertIcon icon,
               bool compact);

source/blender/editors/interface/regions/interface_region_popup.cc

@@ -35,6 +35,8 @@
 #include "interface_intern.hh"
 #include "interface_regions_intern.hh"
 
+using blender::StringRef;
+
 /* -------------------------------------------------------------------- */
 /** \name Utility Functions
  * \{ */
@@ -1124,8 +1126,8 @@ static uiBlock *ui_alert_create(bContext *C, ARegion *region, void *user_data)
 }
 
 void UI_alert(bContext *C,
-              const std::string &title,
-              const std::string &message,
+              const StringRef title,
+              const StringRef message,
               const eAlertIcon icon,
               const bool compact)
 {