feat(db): more parallel awareness for Postgres DB class

[davidlougheed]

also return if initialize()/close() actually init/closed the pool

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (7f31615) to head (4b39b67).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #232   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           52        52           
  Lines         1651      1677   +26     
  Branches       243       248    +5     
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+ Hits          1651      1677   +26     

Files with missing lines	Coverage Δ
bento_lib/db/pg_async.py	100.00% <100.00%> (ø)