Add login_demo() for GraphKBConnection

[mathieulemieux]

see https://www.bcgsc.ca/jira/browse/KBDEV-1328

[codecov-commenter]

Codecov Report

❌ Patch coverage is 31.25000% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.88%. Comparing base (091eddb) to head (8032dd7).
⚠️ Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
pori_python/graphkb/util.py	31.25%	11 Missing ⚠️

❌ Your patch status has failed because the patch coverage (31.25%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #72      +/-   ##
===========================================
- Coverage    83.02%   82.88%   -0.15%     
===========================================
  Files           18       18              
  Lines         2404     2419      +15     
===========================================
+ Hits          1996     2005       +9     
- Misses         408      414       +6     

Flag	Coverage Δ
unittests	82.88% <31.25%> (-0.15%)	⬇️

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[nodrogluap]

Can confirm that this edit works from UCalgary, thanks!