Is your feature request related to a problem? Please describe...

I have a few form elements that don't need a lot of input. For those I'd like to specify their width in "columns". The class assigned to the content is "col", based on the b-col component as it seems, but there's no way to specify these properties when using the b-form-group component.

Describe the solution you'd like

Maybe expose a few props from b-col to b-form-group?

Describe alternatives you've considered

Wrapping it around nested columns, but then I have to specify custom widths per label per form group