Name `up ctx` exported contexts with group and ctp

[RedbackThomson]

What happened?

Currently all contexts exported by up ctx use the name upbound. This context name provides no information about which space, group or control plane the context is pointed at without looking at the full kubeconfig. Ideally we should be putting some of that information into the context name when exporting it.

For example:

• A group should be upbound/<group>
• A ctp should be upbound/<group>/<ctp>

How can we reproduce it?

What environment did it happen in?