core: Shuffle function to get description string from a frame

This will remain used (and mildly useful), so move it outside of src/ui.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2175>

src/core/frame.c

@@ -537,3 +537,38 @@ meta_frame_launch_client (MetaX11Display *x11_display,
 
   return proc;
 }
+
+/**
+ * meta_frame_type_to_string:
+ * @type: a #MetaFrameType
+ *
+ * Converts a frame type enum value to the name string that would
+ * appear in the theme definition file.
+ *
+ * Return value: the string value
+ */
+const char *
+meta_frame_type_to_string (MetaFrameType type)
+{
+  switch (type)
+    {
+    case META_FRAME_TYPE_NORMAL:
+      return "normal";
+    case META_FRAME_TYPE_DIALOG:
+      return "dialog";
+    case META_FRAME_TYPE_MODAL_DIALOG:
+      return "modal_dialog";
+    case META_FRAME_TYPE_UTILITY:
+      return "utility";
+    case META_FRAME_TYPE_MENU:
+      return "menu";
+    case META_FRAME_TYPE_BORDER:
+      return "border";
+    case META_FRAME_TYPE_ATTACHED:
+      return "attached";
+    case  META_FRAME_TYPE_LAST:
+      break;
+    }
+
+  return "<unknown>";
+}

src/ui/theme.c

@@ -1356,42 +1356,3 @@ meta_pango_font_desc_get_text_height (const PangoFontDescription *font_desc,
 
   return retval;
 }
-
-/**
- * meta_frame_type_to_string:
- * @type: a #MetaFrameType
- *
- * Converts a frame type enum value to the name string that would
- * appear in the theme definition file.
- *
- * Return value: the string value
- */
-const char*
-meta_frame_type_to_string (MetaFrameType type)
-{
-  switch (type)
-    {
-    case META_FRAME_TYPE_NORMAL:
-      return "normal";
-    case META_FRAME_TYPE_DIALOG:
-      return "dialog";
-    case META_FRAME_TYPE_MODAL_DIALOG:
-      return "modal_dialog";
-    case META_FRAME_TYPE_UTILITY:
-      return "utility";
-    case META_FRAME_TYPE_MENU:
-      return "menu";
-    case META_FRAME_TYPE_BORDER:
-      return "border";
-    case META_FRAME_TYPE_ATTACHED:
-      return "attached";
-#if 0
-    case META_FRAME_TYPE_TOOLBAR:
-      return "toolbar";
-#endif
-    case  META_FRAME_TYPE_LAST:
-      break;
-    }
-
-  return "<unknown>";
-}