dynamic Router and Cluster from registry center

[FoghostCn]

What this PR does:

dynamic Router and Cluster from registry center

ref #600

Special notes for your reviewer:

support application level and interface level service discovery support zk and nacos registry

application level service discovery use prefix url pattern to match http path,beacuse there is no methods information in the registry.

Does this PR introduce a user-facing change?:

  adapters:
    - id: test
      name: dgp.adapter.dubboregistrycenter
      config:
        registries:
          "zookeeper":
            registry_type: application // new config field, support "application" or "interface" 
            protocol: zookeeper
            address: "127.0.0.1:2181"
            timeout: "5s"

demo project

https://github.com/FoghostCn/dubbo-go-pixiu-samples/blob/feature-registry-center/dubbogo/simple/zookeeper

• dubbo server: server/app/server.go
• test case: test/pixiu_test.go
• pixiu config: pixiu/conf.yaml

static_resources:
  listeners:
    - name: "net/http"
      protocol_type: "HTTP"
      address:
        socket_address:
          address: "0.0.0.0"
          port: 8881
      filter_chains:
        filters:
          - name: dgp.filter.httpconnectionmanager
            config:
              route_config:
                dynamic: true
              http_filters:
                - name: dgp.filter.http.directdubboproxy
                  config:
  adapters:
    - id: test
      name: dgp.adapter.dubboregistrycenter
      config:
        registries:
          "zookeeper":
            registry_type: application # or interface
            protocol: zookeeper
            address: "127.0.0.1:2181"
            timeout: "5s"