Add HTTP Server and gRPC Server

manifests/ztp_server.yaml

proto/ztp_server.proto

src/common/Constants.py

src/ztp_server/Dockerfile

src/ztp_server/README.md

src/ztp_server/client/ZtpClient.py

src/ztp_server/data/nso_client.proto

src/ztp_server/requirements.in

src/ztp_server/service/ZtpServerService.py

src/ztp_server/service/ZtpServerServiceServicerImpl.py

src/ztp_server/service/context_subscription/__init__.py

...ervice/rest_server/ztpServer_plugins/tfs_api/Resources.py

...er/service/rest_server/ztpServer_plugins/tfs_api/Tools.py

src/ztp_server/tests/Constants.py

src/ztp_server/tests/MockService_Dependencies.py

src/ztp_server/tests/PrepareTestScenario.py

src/ztp_server/tests/__init__.py

src/ztp_server/tests/data/ietf_acl.json

src/ztp_server/tests/data/ietf_l3vpn_req_svc1.json

src/ztp_server/tests/data/ietf_l3vpn_req_svc2.json