GRPC error codes, 3 new error types, auto detect context errors

[bnkamalesh]

[minor] added helpers for GRPC status codes and messages
[minor] introduced 3 new error types NotImplemented, ContextCanceled, ContextTimedout
[minor] context errors are automatically identified in error types
[patch] improved test coverage
[-] updated benchmark results

[coveralls]

Pull Request Test Coverage Report for Build 16046726488

Details

• 187 of 214 (87.38%) changed or added relevant lines in 4 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+6.9%) to 80.556%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
errors.go	1	3	33.33%
grpc.go	72	74	97.3%
helper.go	40	63	63.49%

Files with Coverage Reduction	New Missed Lines	%
errors.go	2	83.28%
helper.go	2	68.01%

Totals
Change from base Build 11291483275:	6.9%
Covered Lines:	609
Relevant Lines:	756

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💛 - Coveralls