Allow disabling hiding columns when using wxHeaderCtrl in wxGrid

Add wxGrid::DisableHidingColumns() method which can be used to prevent
wxHeaderCtrl from allowing the user to hide columns interactively, which
is something it allows to do by default, unlike the "built-in" wxGrid
header.

Also add EnableHidingColumns() and CanHideColumns() for consistency with
the other similar methods.

Closes https://github.com/wxWidgets/wxWidgets/pull/1554

interface/wx/grid.h

@@ -3707,6 +3707,13 @@ public:
     */
     bool CanDragRowSize(int row) const;
 
+    /**
+        Returns @true if columns can be hidden from the popup menu of the native header.
+
+        @since 3.1.3
+    */
+    bool CanHideColumns() const;
+
     /**
         Disable interactive resizing of the specified column.
 
@@ -3765,6 +3772,15 @@ public:
     */
     void DisableDragRowSize();
 
+    /**
+        Disables column hiding from the header popup menu.
+
+        Equivalent to passing @false to EnableHidingColumns().
+
+        @since 3.1.3
+    */
+    void DisableHidingColumns();
+
     /**
         Enables or disables cell dragging with the mouse.
     */
@@ -3801,6 +3817,28 @@ public:
     */
     void EnableDragRowSize(bool enable = true);
 
+    /**
+        Enables or disables column hiding from the header popup menu.
+
+        Note that currently the popup menu can only be shown when using
+        wxHeaderCtrl, i.e. if UseNativeColHeader() had been called.
+
+        If the native header is not used, this method always simply returns
+        @false without doing anything, as hiding columns is not supported
+        anyhow. If @a enable value is the same as CanHideColumns(), it also
+        returns @false to indicate that nothing was done. Otherwise, it returns
+        @true to indicate that the value of this option was successfully
+        changed.
+
+        The main use case for this method is to disallow hiding the columns
+        interactively when using the native header.
+
+        @since 3.1.3
+
+        @see DisableHidingColumns()
+    */
+    bool EnableHidingColumns(bool enable = true);
+
     /**
         Returns the column ID of the specified column position.
     */