Domainmapping support dir-path-based routing

Describe the feature

now it's little complex to config routing different dir-path to different ksvc, istio VS should be configured. such as https://github.com/knative/serving/issues/11892,
So I think it's better to config this with domainmapping, like bellows(POC demo coding now):
domaincliam.yaml

root@jw [04:18:19 PM] [~jw/testyaml]
-> # cat domainclaim.yaml
apiVersion: networking.internal.knative.dev/v1alpha1
kind: ClusterDomainClaim
metadata:
  name: test1.com
spec:
  namespace: default

domainmapping.yaml

root@jw [04:18:19 PM] [~jw/testyaml]
-> # cat domainmapping.yaml
apiVersion: serving.knative.dev/v1alpha1
kind: DomainMapping
metadata:
  name: test1.com
  namespace: default
spec:
  ref:
    - match:
      - uri:
        prefix: "/"
        name: home-page
        kind: Service
        apiVersion: serving.knative.dev/v1
    - match:
      - uri:
        prefix: "/search"
        name: search-go
        kind: Service
        apiVersion: serving.knative.dev/v1
    - match:
      - uri:
        prefix: "/login"
        name: login-go
        kind: Service
        apiVersion: serving.knative.dev/v1

This feature maybe just can be done based on istio gateway. Still not deeply check whether other gateways support.

/area API
/assign @julz @mattmoor what do u think of this?

Start with the DomainMapping and ClusterDomainClaim examples in the issue, then review how routing and Istio VirtualServices are currently configured. Determine the supported API shape and gateway implications; done means the project has an agreed design and documented implementation scope for path-based routing.