Decommission libgit2 Unmanaged Transport

[pjbgf]

Decomissions libgit2 Unmanaged Transport and updates the dependencies below:

• k8s.io/api to version 0.24.3.
• k8s.io/apimachinery to version 0.24.3.
• k8s.io/client-go to version 0.24.3.
• github.com/fluxcd/image-reflector-controller/api to version 0.20.0.
• github.com/fluxcd/source-controller to version 0.26.0.
• k8s.io/kube-openapi to version v0.0.0-20220803164354-a70c9af30aea.
• github.com/ProtonMail/go-crypto to version v0.0.0-20220730123233-d6ffb7692adf.
• sigs.k8s.io/kustomize/kyaml to version v0.13.9.

[stefanprodan]

LGTM

Thanks @pjbgf

[aryan9600]

ImageUpdateAutomationReconciler needs to be updated to have Libgit2TransportInitialized as a field (ref: https://github.com/fluxcd/source-controller/blob/v0.26.0/controllers/gitrepository_controller.go#L120) and the reconcile logic needs to verify whether libgit2 transports have been initialized before performing any git operations.

The GitManagedTransport feature needs to be removed from internal/features/features.go

[pjbgf]

@aryan9600 just removed GitManagedTransport, thanks for pointing it out.

For Libgit2TransportInitialized as currently the controller only supports libgit2 this PR exits early in main.go if it can't initialise libgit2. We can review this approach once we all git implementation code is in fluxcd/pkg.

[pjbgf]

This has been tested against GitHub, GitLab and BitBucket. All worked as expected.