Added response info middleware

[vytautas-karpavicius]

What changed?
Added outbound middleware for filling rpc.ResponseInfo structure.

Why?
This can be useful for a general way to obtain information about the response before it gets deserialized and returned to the client. One such example - obtaining serialized size of the message.

Intended usage example:

ctx, responseInfo := rpc.ContextWithResponseInfo(ctx)
resp, err := client.GetReplicationMessages(ctx, request, opts...)
messageSize := responseInfo.Size
...

How did you test it?
Added unit test, verified locally with print statement that message size can be obtained that way.

Potential risks

Release notes

Documentation Changes

[coveralls]

Pull Request Test Coverage Report for Build 415e369e-1251-4764-9541-588c28b36754

• 15 of 15 (100.0%) changed or added relevant lines in 2 files are covered.
• 101 unchanged lines in 11 files lost coverage.
• Overall coverage decreased (-0.02%) to 56.48%

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Files with Coverage Reduction	New Missed Lines	%
service/history/execution/mutable_state_task_refresher.go	1	73.82%
service/history/queue/timer_queue_processor_base.go	1	79.5%
common/task/fifoTaskScheduler.go	2	85.57%
service/history/queue/timer_queue_processor.go	2	59.33%
service/matching/taskListManager.go	2	74.09%
common/persistence/dataManagerInterfaces.go	3	60.91%
common/persistence/nosql/nosqlplugin/cassandra/workflow.go	3	50.23%
common/persistence/nosql/nosqlplugin/cassandra/tasks.go	14	72.8%
common/persistence/nosql/nosqlTaskStore.go	16	58.37%
common/persistence/nosql/nosqlplugin/cassandra/workflowUtils.go	20	77.03%

Totals
Change from base Build 6086fb9c-6671-48f2-9421-25018cdc2d1b:	-0.02%
Covered Lines:	80464
Relevant Lines:	142465

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💛 - Coveralls