Make ctp list derive context from kubeconfig

[Piotr1215]

Description of your changes

This PR makes up ctp list kubeconfig context aware, making it independent from the current profile. The profile is automatically derived:

$ kubectl ctx not-space-kube $ up ctp list You are not on a space. $ kubectl ctx space $ up ctp list .... controlplanes from the profile matching the kubeconfig context's URL .... $ up ctp connect ctp $ up ctp list In a controlplane, you cannot list controlplanes. Use 'up ctx ..' to go to group level.

Fixes https://github.com/upbound/spaces/issues/752

NOTE: this breaks the use against a cloud profile. We will bring it back in a follow-up.

I have:

• [x] Read and followed Upbound's contribution process.
• [x] Run make reviewable to ensure this PR is ready for review.
• [ ] ~Added backport release-x.y labels to auto-backport this PR, as appropriate.~

How has this code been tested

This can be tested locally by running the following setup:

• create local kind cluster with spaces
• create empty kind cluster
• follow the command logic from description