FontEditor: Remove code duplication when resizing GlyphEditor

The left column now also enforces a minimum width to prevent especially
small fonts from hiding the glyph toolbars and width widgets.

Userland/Applications/FontEditor/FontEditor.h

@@ -43,6 +43,7 @@ private:
     void undo();
     void redo();
     void did_modify_font();
+    void did_resize_glyph_editor();
     void update_statusbar();
     void update_preview();