Introduction of protoc-gen-yarpc-go-v2 plugin compatible with golang protobuf v2

[gandhikrishna]

• [x] Description and context for reviewers: one partner, one stranger
• [x] Entry in CHANGELOG.md

This PR aims to add a new yarpc plugin compatible with golang protobuf v2 APIs. All code in this PR has been reviewed separately in the below pull request:

https://github.com/yarpc/yarpc-go/pull/2160 https://github.com/yarpc/yarpc-go/pull/2159 https://github.com/yarpc/yarpc-go/pull/2158 https://github.com/yarpc/yarpc-go/pull/2157 https://github.com/yarpc/yarpc-go/pull/2153 https://github.com/yarpc/yarpc-go/pull/2136 https://github.com/yarpc/yarpc-go/pull/2125 https://github.com/yarpc/yarpc-go/pull/2124 https://github.com/yarpc/yarpc-go/pull/2123 https://github.com/yarpc/yarpc-go/pull/2118 https://github.com/yarpc/yarpc-go/pull/2114

Test Plan:

• Code generation template is been tested by generating yarpc protobuf stubs.
• Integration test for yarpc inbound/outbound and protobuf compatibility with golang protobuf v2.
• Unit test for error APIs.

[codecov[bot]]

Codecov Report

Base: 87.69% // Head: 85.14% // Decreases project coverage by -2.54% :warning:

Coverage data is based on head (025c641) compared to base (a1a51b8). Patch coverage: 45.96% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #2164 +/- ## ========================================== - Coverage 87.69% 85.14% -2.55% ========================================== Files 254 268 +14 Lines 14315 15244 +929 ========================================== + Hits 12554 12980 +426 - Misses 1362 1842 +480 - Partials 399 422 +23 ``` | [Impacted Files](https://codecov.io/gh/yarpc/yarpc-go/pull/2164?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc) | Coverage Δ | | |---|---|---| | [...rotobuf/protoc-gen-yarpc-go-v2/internal/lib/lib.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-ZW5jb2RpbmcvcHJvdG9idWYvcHJvdG9jLWdlbi15YXJwYy1nby12Mi9pbnRlcm5hbC9saWIvbGliLmdv) | `0.00% <0.00%> (ø)` | | | [encoding/protobuf/protoc-gen-yarpc-go-v2/main.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-ZW5jb2RpbmcvcHJvdG9idWYvcHJvdG9jLWdlbi15YXJwYy1nby12Mi9tYWluLmdv) | `0.00% <0.00%> (ø)` | | | [internal/protoplugin-v2/generator.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-aW50ZXJuYWwvcHJvdG9wbHVnaW4tdjIvZ2VuZXJhdG9yLmdv) | `0.00% <0.00%> (ø)` | | | [internal/protoplugin-v2/protoplugin.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-aW50ZXJuYWwvcHJvdG9wbHVnaW4tdjIvcHJvdG9wbHVnaW4uZ28=) | `2.63% <2.63%> (ø)` | | | [internal/protoplugin-v2/runner.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-aW50ZXJuYWwvcHJvdG9wbHVnaW4tdjIvcnVubmVyLmdv) | `8.51% <8.51%> (ø)` | | | [internal/protoplugin-v2/registry.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-aW50ZXJuYWwvcHJvdG9wbHVnaW4tdjIvcmVnaXN0cnkuZ28=) | `10.05% <10.05%> (ø)` | | | [encoding/protobuf/v2/inbound.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-ZW5jb2RpbmcvcHJvdG9idWYvdjIvaW5ib3VuZC5nbw==) | `55.17% <55.17%> (ø)` | | | [encoding/protobuf/v2/outbound.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-ZW5jb2RpbmcvcHJvdG9idWYvdjIvb3V0Ym91bmQuZ28=) | `58.76% <58.76%> (ø)` | | | [encoding/protobuf/v2/protobuf.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-ZW5jb2RpbmcvcHJvdG9idWYvdjIvcHJvdG9idWYuZ28=) | `75.25% <75.25%> (ø)` | | | [internal/protoplugin-v2/utils.go](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc#diff-aW50ZXJuYWwvcHJvdG9wbHVnaW4tdjIvdXRpbHMuZ28=) | `91.66% <91.66%> (ø)` | | | ... and [5 more](https://codecov.io/gh/yarpc/yarpc-go/pull/2164/diff?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yarpc)

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