`generateGroupId` prop to the TreeDataGrid component

[Luisgustavom1]

• Add the generateGroupId prop to the TreeDataGrid component.
• This prop allows developers to generate custom group IDs based on their own logic.
• The generateGroupId function takes a groupKey and parentId params as input and returns a generated group ID.
• This prop provides flexibility in generating unique group IDs for each row in the grid.

Implementation already is done: https://github.com/adazzle/react-data-grid/pull/3520