[feat] Allow logging arbitrary job attributes

[vkarak]

This PR allows users to log arbitrary attributes of the run job associated with the currently executing test by using the %(check_job_ATTR)s log format specifier. For example, users can log the node list that the job has run on by specifying %(check_job_nodelist)s.

Fixes #1729.

[ekouts]

lgtm

[codecov-io]

Codecov Report

Merging #1788 (25e3f77) into master (0883ee3) will increase coverage by 0.03%.
The diff coverage is 90.00%.

@@            Coverage Diff             @@
##           master    #1788      +/-   ##
==========================================
+ Coverage   87.36%   87.40%   +0.03%     
==========================================
  Files          47       47              
  Lines        7765     7780      +15     
==========================================
+ Hits         6784     6800      +16     
+ Misses        981      980       -1     

Impacted Files	Coverage Δ
reframe/core/pipeline.py	92.16% <ø> (ø)
reframe/core/containers.py	97.64% <50.00%> (-2.36%)	⬇️
reframe/core/logging.py	84.52% <100.00%> (+0.13%)	⬆️
reframe/utility/__init__.py	91.91% <100.00%> (+0.12%)	⬆️
reframe/core/schedulers/slurm.py	52.71% <0.00%> (+0.27%)	⬆️
reframe/core/schedulers/__init__.py	98.34% <0.00%> (+0.55%)	⬆️
reframe/core/schedulers/local.py	96.63% <0.00%> (+0.84%)	⬆️

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