Pretty name for sort by field

[Pasqualle]

• Fixed the name of the sort by field.
• Fixed some comments.
• Found a bug in getContextualArguments() function.

Untested code..

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (8.x-1.x@40d0a16). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff             @@
##             8.x-1.x      #10   +/-   ##
==========================================
  Coverage           ?   77.06%           
==========================================
  Files              ?       23           
  Lines              ?      702           
  Branches           ?        0           
==========================================
  Hits               ?      541           
  Misses             ?      161           
  Partials           ?        0

Impacted Files	Coverage Δ
src/Plugin/views/display/GraphQL.php	43.2% <100%> (ø)
src/Plugin/Deriver/Fields/ViewDeriver.php	98.36% <100%> (ø)
src/Plugin/Deriver/Enums/ViewSortByDeriver.php	95.23% <100%> (ø)

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[fubhy]

Thanks for the pull request and sorry for not checking it out earlier. The names of the types should be fixed already.