[RFR] Introduce Datagrid rowClick

[fzaninotto]

Some users require datagrids with many columns. The Edit or Show button takes a significant share of the horizontal space. As an alternative to adding an <EditButton>, developers can now enable the rowClick option on the <Datagrid> component:

const UserList = props => (
    <List {...props}>
        <Datagrid rowClick="show">
            <TextField source="id" />
            <TextField source="name" />
            <TextField source="role" />
        </Datagrid>
    </List>
);