Constructs a ColumnHeaderMenuDecorator instance — end-users will never need to do this themselves since grids are fully constructed based on their XML definition files by the module:ct-grid/GridGenerator class.

The ColumnMenuDecorator adds a menu to each column that allows the user to add or remove columns as necessary. The columns that can be added or removed are controlled entirely from the XML configuration that is used to construct the module:ct-grid/GridColumnModel. This includes whether a column is mandatory or not.