Ported job calculation to use coroutines for tasks

[muhrin]

Fixes #1828

This way the event loop has a chance to schedule other operations while
a transport request is made i.e. if multiple job calculations all
request the same transport (a common scenario) then in the past they
would all run as one loop callback effectively blocking the loop (and
crucially pika heartbeats). Now they are schedule as seperate callbacks
thanks to yield, hopefully, allowing the loop to schedule other
necessary tasks in between.

[codecov-io]

Codecov Report

Merging #1827 into develop will increase coverage by 8.52%.
The diff coverage is 87.75%.

@@             Coverage Diff             @@
##           develop    #1827      +/-   ##
===========================================
+ Coverage    58.16%   66.68%   +8.52%     
===========================================
  Files          317      317              
  Lines        32394    32409      +15     
===========================================
+ Hits         18843    21613    +2770     
+ Misses       13551    10796    -2755

Impacted Files	Coverage Δ
aiida/transport/transport.py	62.2% <66.66%> (+0.36%)	⬆️
aiida/work/transports.py	90.56% <89.13%> (+45.56%)	⬆️
aiida/orm/querybuilder.py	74.16% <0%> (+0.24%)	⬆️
aiida/common/setup.py	74.63% <0%> (+0.41%)	⬆️
aiida/control/computer.py	80.9% <0%> (+0.9%)	⬆️
aiida/orm/implementation/general/node.py	78.5% <0%> (+0.95%)	⬆️
aiida/orm/implementation/general/group.py	60.82% <0%> (+1.03%)	⬆️
aiida/common/hashing.py	83.87% <0%> (+1.07%)	⬆️
aiida/orm/implementation/django/authinfo.py	82.85% <0%> (+1.42%)	⬆️
... and 42 more

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[sphuber]

Merge transport request granted