Improve parsing --jobs and --credits options

[serhiy-storchaka]

Closes #2453 and #2454.

[codecov]

Codecov Report

Merging #2458 (07fcf4b) into master (5876f41) will increase coverage by 0.23%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2458      +/-   ##
==========================================
+ Coverage   75.32%   75.56%   +0.23%     
==========================================
  Files          66       66              
  Lines       10711    10726      +15     
  Branches     2075     2078       +3     
==========================================
+ Hits         8068     8105      +37     
+ Misses       2346     2325      -21     
+ Partials      297      296       -1     

Impacted Files	Coverage Δ
neuro-cli/src/neuro_cli/admin.py	65.34% <100.00%> (+8.74%)	⬆️
neuro-cli/src/neuro_cli/formatters/config.py	100.00% <100.00%> (ø)
neuro-cli/src/neuro_cli/log_formatter.py	82.85% <0.00%> (+5.71%)	⬆️

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