[VOL-2193] Create mocks for Kafka Client and Etcd

This commit consists of:
1) A kafka client mock that implements the kafka client interface
under voltha-lib-go/pkg/kafka/client.go
2) An embedded Etcd server that runs in-process and represents an
Etcd server.

Change-Id: I52a36132568e08c596bb4136918bebcb654a3b99
diff --git a/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/member.go b/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/member.go
new file mode 100644
index 0000000..b2ebc98
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/etcdserver/api/v3rpc/member.go
@@ -0,0 +1,119 @@
+// Copyright 2016 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v3rpc
+
+import (
+	"context"
+	"time"
+
+	"go.etcd.io/etcd/etcdserver"
+	"go.etcd.io/etcd/etcdserver/api"
+	"go.etcd.io/etcd/etcdserver/api/membership"
+	"go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
+	pb "go.etcd.io/etcd/etcdserver/etcdserverpb"
+	"go.etcd.io/etcd/pkg/types"
+)
+
+type ClusterServer struct {
+	cluster api.Cluster
+	server  etcdserver.ServerV3
+}
+
+func NewClusterServer(s etcdserver.ServerV3) *ClusterServer {
+	return &ClusterServer{
+		cluster: s.Cluster(),
+		server:  s,
+	}
+}
+
+func (cs *ClusterServer) MemberAdd(ctx context.Context, r *pb.MemberAddRequest) (*pb.MemberAddResponse, error) {
+	urls, err := types.NewURLs(r.PeerURLs)
+	if err != nil {
+		return nil, rpctypes.ErrGRPCMemberBadURLs
+	}
+
+	now := time.Now()
+	var m *membership.Member
+	if r.IsLearner {
+		m = membership.NewMemberAsLearner("", urls, "", &now)
+	} else {
+		m = membership.NewMember("", urls, "", &now)
+	}
+	membs, merr := cs.server.AddMember(ctx, *m)
+	if merr != nil {
+		return nil, togRPCError(merr)
+	}
+
+	return &pb.MemberAddResponse{
+		Header: cs.header(),
+		Member: &pb.Member{
+			ID:        uint64(m.ID),
+			PeerURLs:  m.PeerURLs,
+			IsLearner: m.IsLearner,
+		},
+		Members: membersToProtoMembers(membs),
+	}, nil
+}
+
+func (cs *ClusterServer) MemberRemove(ctx context.Context, r *pb.MemberRemoveRequest) (*pb.MemberRemoveResponse, error) {
+	membs, err := cs.server.RemoveMember(ctx, r.ID)
+	if err != nil {
+		return nil, togRPCError(err)
+	}
+	return &pb.MemberRemoveResponse{Header: cs.header(), Members: membersToProtoMembers(membs)}, nil
+}
+
+func (cs *ClusterServer) MemberUpdate(ctx context.Context, r *pb.MemberUpdateRequest) (*pb.MemberUpdateResponse, error) {
+	m := membership.Member{
+		ID:             types.ID(r.ID),
+		RaftAttributes: membership.RaftAttributes{PeerURLs: r.PeerURLs},
+	}
+	membs, err := cs.server.UpdateMember(ctx, m)
+	if err != nil {
+		return nil, togRPCError(err)
+	}
+	return &pb.MemberUpdateResponse{Header: cs.header(), Members: membersToProtoMembers(membs)}, nil
+}
+
+func (cs *ClusterServer) MemberList(ctx context.Context, r *pb.MemberListRequest) (*pb.MemberListResponse, error) {
+	membs := membersToProtoMembers(cs.cluster.Members())
+	return &pb.MemberListResponse{Header: cs.header(), Members: membs}, nil
+}
+
+func (cs *ClusterServer) MemberPromote(ctx context.Context, r *pb.MemberPromoteRequest) (*pb.MemberPromoteResponse, error) {
+	membs, err := cs.server.PromoteMember(ctx, r.ID)
+	if err != nil {
+		return nil, togRPCError(err)
+	}
+	return &pb.MemberPromoteResponse{Header: cs.header(), Members: membersToProtoMembers(membs)}, nil
+}
+
+func (cs *ClusterServer) header() *pb.ResponseHeader {
+	return &pb.ResponseHeader{ClusterId: uint64(cs.cluster.ID()), MemberId: uint64(cs.server.ID()), RaftTerm: cs.server.Term()}
+}
+
+func membersToProtoMembers(membs []*membership.Member) []*pb.Member {
+	protoMembs := make([]*pb.Member, len(membs))
+	for i := range membs {
+		protoMembs[i] = &pb.Member{
+			Name:       membs[i].Name,
+			ID:         uint64(membs[i].ID),
+			PeerURLs:   membs[i].PeerURLs,
+			ClientURLs: membs[i].ClientURLs,
+			IsLearner:  membs[i].IsLearner,
+		}
+	}
+	return protoMembs
+}