Outbound channel close error is propagated to stream

[marcoferrer]

This PR resolves issue #93

[codecov-io]

Codecov Report

Merging #95 into master will increase coverage by 0.91%.
The diff coverage is 85.18%.

@@             Coverage Diff              @@
##             master      #95      +/-   ##
============================================
+ Coverage     85.62%   86.53%   +0.91%     
  Complexity       19       19              
============================================
  Files            15       15              
  Lines           306      312       +6     
  Branches         49       53       +4     
============================================
+ Hits            262      270       +8     
  Misses           15       15              
+ Partials         29       27       -2

Impacted Files	Coverage Δ	Complexity Δ
...oferrer/krotoplus/coroutines/client/ClientCalls.kt	87.17% <ø> (ø)	0 <0> (ø)	⬇️
...utines/call/FlowControlledInboundStreamObserver.kt	82.6% <ø> (+3.44%)	0 <0> (ø)	⬇️
.../marcoferrer/krotoplus/coroutines/call/CallExts.kt	84.84% <83.33%> (-3.04%)	0 <0> (ø)
...rcoferrer/krotoplus/coroutines/call/FlowControl.kt	89.18% <86.66%> (+2.52%)	0 <0> (ø)	⬇️
...s/coroutines/client/ClientResponseStreamChannel.kt	100% <0%> (+14.28%)	9% <0%> (ø)	⬇️

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[marcoferrer]

I still need to add notes for the reason behind closing outbound channels with an error before cancelling it in the client channel impls. If we close a channel with our server error before cancelling it then we can ensure that any user code that is attempting to send on the outbound channel will throw the server exception. Cancel is just a means to free up the outbound message handler so that our coroutine scope can complete.

I also still need to add tests exercising this use case.
Client Tests: Client Streaming, BidiStreaming
Server Tests: Server Streaming, BidiStreaming