React-admin: Support row expansion on DataGrid row-click

[kdabir]

Is your feature request related to a problem? Please describe.
Currently, rowClick supports show|edit as possible action on click of DataGrid row.

Describe the solution you'd like
Please consider supporting additional option value expand which is will expand the row.

<Datagrid rowClick="expand" expand={<GroupExpansion/>}>

Additional context
Row Expansion was a feature introduced in 2.6.

[fzaninotto]

Nice suggestion. We won't implement it ourselves as we don't need it, so feel free to open a PR about it.

[fzaninotto]

It turns out we do need it now ;)

[fzaninotto]

Fixed by #2820