fix(kuma-cp) ingress per cluster (not per mesh)

[lobkovilya]

Summary

This PR fixes the limitation that we currently have. Instead of having ingress per mesh, we will have ingress per cluster.
In order to achieve it we do the following things:

1. During reconcile of available services, we also add mesh for each service. I did it using tags, but that also could be a separate field if needed. So now availableServices looks like this:

availableServices:
  - tags:
       mesh: kuma-demo
       service: backend
       version: v2
    instances: 1
  - tags:
       mesh: banking
       service: payments
       version: v1
    instances: 1

2. During resource generation for Envoy we split one multi-mesh Ingress into several Ingresses each of them has available services just for the single mesh. It is needed to do only minor changes in the code that generates outbounds. So ingress above will be split into:

mesh: kuma-demo
type: Dataplane
name: ingress
networking:
  ingress:
    availableServices:
      - tags:
           mesh: kuma-demo
           service: backend
           version: v2
         instances: 1

and

mesh: banking
type: Dataplane
name: ingress
networking:
  ingress:
    availableServices:
      - tags:
           mesh: banking
           service: payment
           version: v1
         instances: 1

3. When generate outboundTargets, endpoints should match Tags from Destination map. In order to do it, Endpoints should have tag mesh as well.

4. Tag mesh should also be a part of SNI.

Full changelog

• Multi-mesh Ingress
• This PR also has a couple of tests not related to Ingress, they were omitted during KDS implementation

Issues resolved

Fix #835

Documentation

• Link to the website documentation PR

[nickolaev]

Insignificant nits on my side. Overall looks good.