Expose more of Cilium's core features

[namsral]

/area networking
/kind enhancement

What would you like to be added:

I work for a public cloud provider utilizing OpenStack and my customers have asked if the following Cilium features could be exposed when deploying shoot clusters:

• External workloads
• Service meshing
• BGP routing
• VXLAN

Why is this needed:

This is needed for users who want to connect their current infrastructure with a shoot cluster. A popular use case is to connect privately run datastores to shoot cluster worker nodes. Another use case is when transitioning workloads from on-site to Kubernetes.

[jochbru]

It would be super useful for us to just be able to configure cilium through the Shoot definitions.