Show GitOps source information on cluster details in Backstage

[marians]

User story

As a cluster admin, I want to quickly find the GitOps source for a cluster from the developer portal, so that I can inspect and modify details or view the modification history.

Details

We want to

• highlight the fact that a cluster is defined in a git source, and we want to
• enable quick navigation to that source.

In the context of https://github.com/giantswarm/giantswarm/issues/31921 we have discussed how to determine that a cluster is gitops-managed.

In addition, we would like to provide a direct link for end users to jump to the source in a web UI.

Example

For the operations workload cluster in installation gazelle, we want to show this link.

This link get composed out of several parts:

• Base part: e. g. https://github.com/giantswarm/workload-clusters-fleet/
• UI specific path snippet, e. g. tree/main/
• Directory or file path within the git repository: management-clusters/gazelle/organizations/giantswarm-production/workload-clusters/operations

The first two parts might be static configuration in Backstage. The third part however must be provided per cluster.