* logging: add AddFields

Support the similar helpers from the v1 introduced in #91:
- [ctxzap.AddFields](https://github.com/grpc-ecosystem/go-grpc-middleware/blob/v1/logging/zap/ctxzap/context.go#L23-L32)
- [ctxlogrus.AddFields](https://github.com/grpc-ecosystem/go-grpc-middleware/blob/v1/logging/logrus/ctxlogrus/context.go#L22-L30)
- [ctxkit.AddFields](https://github.com/grpc-ecosystem/go-grpc-middleware/blob/v1/logging/kit/ctxkit/context.go#L22-L28)

Signed-off-by: Olivier Cano <[email protected]>

* Update interceptors/logging/logging.go

Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

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Signed-off-by: Olivier Cano <[email protected]>
Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

Signed-off-by: Olivier Cano <[email protected]>

Closes #741

* grpc_retry backoff overflow

* Add bounds to exponentBase2 and use it instead of math.Exp2

* Add a few tests

* Add copyright to backoff_test

* defer cancel() leaks memory

* Update interceptors/retry/retry.go

Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

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Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

* interceptors/protovalidate: support protovalidate-go.Validator interface

Signed-off-by: Koichi Shiraishi <[email protected]>

* testing/testpb: revert regenerate pb

Signed-off-by: Koichi Shiraishi <[email protected]>

* go.mod: revert add toolchain directive

Signed-off-by: Koichi Shiraishi <[email protected]>

* Revert "go.mod: revert add toolchain directive"

This reverts commit 7ba0f46.

Signed-off-by: Koichi Shiraishi <[email protected]>

---------

Signed-off-by: Koichi Shiraishi <[email protected]>

* README: fix doc replacing

* modernize CI

* Update golang.org deps

* Update tool deps

* Fix lint errors

* Fix test errors

A 32bit binary could not be built because `1 << 62` would overflow the
return `uint` type, as it is an architecture dependent type.

Closes #752

* add build tag to disable tracing

* add new build tag `-build=retrynotrace` to support dead code elimination

* fix copyright headers

* Update interceptors/retry/trace_notrace.go

Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>

* add interceptors/retry/README.md

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Co-authored-by: Johan Brandhorst-Satzkorn <[email protected]>