Client connection pools

[vigoo]

Resolves #1479

TODO:

• [x] Web socket support is broken possibly due to the dynamic handler registration
• [x] Try to revert the channel after closed web socket for reuse, or invalidate it in the pool if that is not possible
• [x] Check if the current handlers already automatically handle the connect/keep-alive headers or if it has to be added
• [x] Invalidate the failed channels in the pool
• [x] Configuration for the pools
• [x] Cleanup
• [x] Tons of tests

[codecov-commenter]

Codecov Report

Base: 59.23% // Head: 59.70% // Increases project coverage by +0.47% :tada:

Coverage data is based on head (8c52b48) compared to base (bdad790). Patch coverage: 77.30% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1493      +/-   ##
==========================================
+ Coverage   59.23%   59.70%   +0.47%     
==========================================
  Files         111      113       +2     
  Lines        3949     4053     +104     
  Branches      117      118       +1     
==========================================
+ Hits         2339     2420      +81     
- Misses       1610     1633      +23     

Impacted Files	Coverage Δ
zio-http/src/main/scala/zio/http/Channel.scala	61.53% <ø> (ø)
...ain/scala/zio/http/netty/NettyFutureExecutor.scala	85.71% <ø> (ø)
...io-http/src/main/scala/zio/http/ClientConfig.scala	58.82% <33.33%> (-7.85%)	:arrow_down:
...ttp/netty/client/ClientResponseStreamHandler.scala	62.50% <50.00%> (-37.50%)	:arrow_down:
...p/netty/client/ClientInboundStreamingHandler.scala	87.50% <60.00%> (-2.50%)	:arrow_down:
...n/scala/zio/http/netty/client/ConnectionPool.scala	71.08% <71.08%> (ø)
...a/zio/http/netty/client/ClientInboundHandler.scala	80.76% <87.50%> (+7.43%)	:arrow_up:
zio-http/src/main/scala/zio/http/ZClient.scala	49.25% <97.56%> (+3.79%)	:arrow_up:
zio-http/src/main/scala/zio/http/Response.scala	79.16% <100.00%> (ø)
...ain/scala/zio/http/netty/client/ChannelState.scala	100.00% <100.00%> (ø)
... and 1 more

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[jdegoes]

@vigoo Should we just merge this?

[vigoo]

If it's ok that it depends on a snapshot ZIO version we can merge it, otherwise wait for 2.0.3