Feature/allow leading space

[sgryphon]

Closes #1040

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• Adapted tests
• Documentation updated
• Created issue to update Templates: {ISSUE_NUMBER}

[maurei]

Thanks for your input! @bart-degreed is on vacation currently, I'd like to have him have a look at it too once he returns. But for the meanwhile I've left some comments for you to look into.

[codecov]

Codecov Report

Merging #1041 (205223e) into master (ea16aaf) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1041   +/-   ##
=======================================
  Coverage   89.95%   89.95%           
=======================================
  Files         257      257           
  Lines        7026     7026           
=======================================
  Hits         6320     6320           
  Misses        706      706           

Impacted Files	Coverage Δ
...NetCore/Queries/Internal/Parsing/QueryTokenizer.cs	100.00% <100.00%> (ø)

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[bart-degreed]

Looks good to me. Thanks for your contribution!