Fix for issues 9653, 22297 

This is a fix for the System.ObjectDisposedException caused by editing a text cell in a DataGridView control a second time.
The issue was caused by calling dispose on a static DataGridViewTextBoxEditingControl object after it has been set as the editingControl for the DataGridView

The full explanation of the cause of this issue is located in this comment https://bugzilla.xamarin.com/show_bug.cgi?id=9653#c5