fix #257: Retry once in case of AbortedException/IOException

[violetagg]

When HttpClient receives AbortedException/IOException, it will retry once
and then will return the exception so that the user can decide how many
retries to do and with what delay.

[codecov-io]

Codecov Report

Merging #272 into master will decrease coverage by 0.08%.
The diff coverage is 0%.

@@             Coverage Diff             @@
##             master    #272      +/-   ##
===========================================
- Coverage     67.58%   67.5%   -0.09%     
+ Complexity     1009    1005       -4     
===========================================
  Files            73      73              
  Lines          4261    4262       +1     
  Branches        605     605              
===========================================
- Hits           2880    2877       -3     
- Misses         1018    1021       +3     
- Partials        363     364       +1

Impacted Files	Coverage Δ	Complexity Δ
.../ipc/netty/http/client/MonoHttpClientResponse.java	77.02% <0%> (-1.06%)	6 <0> (ø)
...or/ipc/netty/http/client/HttpClientOperations.java	54.15% <0%> (-1.61%)	71% <0%> (-2%)
...a/reactor/ipc/netty/channel/ChannelOperations.java	81.95% <0%> (-1.51%)	47% <0%> (-1%)
...or/ipc/netty/http/server/HttpServerOperations.java	67.85% <0%> (-0.6%)	46% <0%> (-1%)
...or/ipc/netty/channel/ChannelOperationsHandler.java	62.93% <0%> (-0.24%)	56% <0%> (-1%)
.../ipc/netty/channel/PooledClientContextHandler.java	63.41% <0%> (ø)	24% <0%> (-2%)	⬇️
...ctor/ipc/netty/resources/DefaultPoolResources.java	78.87% <0%> (+4.22%)	9% <0%> (+1%)	⬆️
...ctor/ipc/netty/http/server/CompressionHandler.java	82.14% <0%> (+7.14%)	20% <0%> (+2%)	⬆️

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[smaldini]

micro optimization: we can invert the condition order to check the volatile only when AbortedException.

[violetagg]

done