GitLab Kubernetes Agent: provide custom certificates to the Agent

Problem to solve

When using GitLab Kubernetes Agent, it is not possible to provide a custom certificate to the Agent component. It should be possible to do it because some GitLab instances are using self-signed certificates and internal CA certificates.

Proposal

We need to implement the method of adding custom certificates to GitLab Kubernetes Agent to make sure that the Agent can communicate with GitLab instances that utilize self-signed certificates or internal CA certificates.

Further details

It could be something similar to what we do for GitLab runner: Providing a custom certificate for accessing GitLab

Permissions and Security

Documentation

Availability & Testing

What does success look like, and how can we measure that?

What is the type of buyer?

Is this a cross-stage feature?

Links / references

cc @ash2k