Fix roundtrip of Parse/ToString for include query string parameters

[bkoelman]

Removes duplicate entries from IncludeExpression.ToString() (caused by derived relationships expansion).
Add tests for the full chain elements, including their types.

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• Adapted tests
• N/A: Documentation updated

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.06%. Comparing base (e9cb483) to head (58e00cf).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1754   +/-   ##
=======================================
  Coverage   92.06%   92.06%           
=======================================
  Files         475      475           
  Lines       14699    14699           
  Branches     2322     2322           
=======================================
  Hits        13533    13533           
  Misses        765      765           
  Partials      401      401           

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