tracing: tracer integration with Apache SkyWalking SDK (#14493)

Fix #13799. This means integration with external Apache SkyWalking SDK for C++ and destroyed redundant parts of implementations. Hired library is https://github.com/skyAPM/cpp2sky. But it is not released and some of missing parts of implementations which are necessary to achieve clean integration. Currently working private fork of that SDK here. https://github.com/Shikugawa/cpp2sky-envoy.

Additional Description:

cpp2sky dependency policy check list

### MUST
- [x] Cloud Native Computing Foundation (CNCF) approved license
- [x] Dependencies must not substantially increase the binary size unless they are optional (i.e. confined to specific extensions)
- [x] No duplication of existing dependencies
       Maybe, the dependencies are described [here](https://github.com/SkyAPM/cpp2sky/blob/main/bazel/repositories.bzl)
- [x] Hosted on a git repository and the archive fetch must directly reference this repository. We will NOT support intermediate artifacts built by-hand located on GCS, S3, etc.
- [x] CVE history appears reasonable, no pathological CVE arcs
- [x] Code review (ideally PRs) before merge
- [x] Security vulnerability process exists, with contact details and reporting/disclosure process
- [x] Tests run in CI

### SHOULD
- [ ] > 1 contributor responsible for a non-trivial number of commits
- [ ] High test coverage (also static/dynamic analysis, fuzzing)
      Parts which is used in Envoy have higher test coverage. But gRPC async segment reporter(which is not used in Envoy) has less test.
- [ ] Envoy can obtain advanced notification of vulnerabilities or of security releases
- [ ] Do other significant projects have shared fate by using this dependency?
- [x] Releases (with release notes)
- [x] Commits/releases in last 90 days

Risk Level: Mid
Testing: Unit/Integration
Docs Changes:
Release Notes:
Platform Specific Features:

Signed-off-by: Shikugawa <rei@tetrate.io>

Mirrored from https://github.com/envoyproxy/envoy @ 032a8e75928304e011833babea2ca231f32866dd

bazel/repositories.bzl

@@ -40,10 +40,6 @@ def api_dependencies():
         name = "com_github_openzipkin_zipkinapi",
         build_file_content = ZIPKINAPI_BUILD_CONTENT,
     )
-    external_http_archive(
-        name = "com_github_apache_skywalking_data_collect_protocol",
-        build_file_content = SKYWALKING_DATA_COLLECT_PROTOCOL_BUILD_CONTENT,
-    )
 
 PROMETHEUSMETRICS_BUILD_CONTENT = """
 load("@envoy_api//bazel:api_build_system.bzl", "api_cc_py_proto_library")
@@ -105,30 +101,3 @@ go_proto_library(
     visibility = ["//visibility:public"],
 )
 """
-
-SKYWALKING_DATA_COLLECT_PROTOCOL_BUILD_CONTENT = """
-load("@rules_proto//proto:defs.bzl", "proto_library")
-load("@rules_cc//cc:defs.bzl", "cc_proto_library")
-load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
-
-proto_library(
-    name = "protocol",
-    srcs = [
-        "common/Common.proto",
-        "language-agent/Tracing.proto",
-    ],
-    visibility = ["//visibility:public"],
-)
-
-cc_proto_library(
-    name = "protocol_cc_proto",
-    deps = [":protocol"],
-    visibility = ["//visibility:public"],
-)
-
-go_proto_library(
-    name = "protocol_go_proto",
-    proto = ":protocol",
-    visibility = ["//visibility:public"],
-)
-"""

bazel/repository_locations.bzl

@@ -96,15 +96,4 @@ REPOSITORY_LOCATIONS_SPEC = dict(
         release_date = "2020-08-17",
         use_category = ["api"],
     ),
-    com_github_apache_skywalking_data_collect_protocol = dict(
-        project_name = "SkyWalking API",
-        project_desc = "SkyWalking's language independent model and gRPC API Definitions",
-        project_url = "https://github.com/apache/skywalking-data-collect-protocol",
-        version = "8.1.0",
-        sha256 = "ebea8a6968722524d1bcc4426fb6a29907ddc2902aac7de1559012d3eee90cf9",
-        strip_prefix = "skywalking-data-collect-protocol-{version}",
-        urls = ["https://github.com/apache/skywalking-data-collect-protocol/archive/v{version}.tar.gz"],
-        release_date = "2020-07-29",
-        use_category = ["api"],
-    ),
 )