[DMN Designer] Automatically show (Name) edit control when adding new ContextEntries

When a new ContextEntry is added the User must double click on the Name cell to change the default value.

mmortari@redhat.com suggested it would be good if the Name editor was automatically shown and focused when the User creates a new ContextEntry.

Manual Acceptance test

For each column/row agreed in comments that should support this feature:

• Append row/column, fill name, save reopen, check value stored
• Try undo/redo after appending row/column
• Add multiple items in row, check always the last is edited