Add PoolStateMachine.RequestQueue

[fabianfett]

• Add PoolStateMachine.RequestQueue
• Add PoolStateMachine struct (without implementation)
• Add PoolConfiguration which is a config object for PoolStateMachine

[codecov-commenter]

Codecov Report

Merging #424 (3b7c35e) into main (8babbcf) will increase coverage by 0.66%.
The diff coverage is 76.31%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #424      +/-   ##
==========================================
+ Coverage   55.72%   56.38%   +0.66%     
==========================================
  Files         116      118       +2     
  Lines        8050     8087      +37     
==========================================
+ Hits         4486     4560      +74     
+ Misses       3564     3527      -37     

Files	Coverage Δ
...urces/ConnectionPoolModule/ConnectionRequest.swift	60.00% <ø> (+60.00%)	⬆️
.../ConnectionPoolModule/OneElementFastSequence.swift	100.00% <100.00%> (ø)
...tionPoolModule/PoolStateMachine+RequestQueue.swift	100.00% <100.00%> (ø)
...ources/ConnectionPoolModule/PoolStateMachine.swift	0.00% <0.00%> (ø)

... and 2 files with indirect coverage changes