Interacting with a profile_list's nested server options should select the server

[consideRatio]

@jbusecke reported this experience, and I think it makes for a good improvement of KubeSpawner's profile_list profile_options feature.

Currently I can select an image on e.g. the medium server, but the default radio button selection will still be on a small server.

I think it would make a lot of sense to automatically select whichever instance the drop down is attached to, once the drop down is selected?

Each entry in the profile_list can have additional options as configured under the profile_list list entry's profile_options. Interaction with such options should switch the radio button to select the profile_list entry having those profile_options.

[jbusecke]

All credit for raising this goes to @RobertPincus 😀