Fix Craft 5.6+ compatibility

[brandonkelly]

EntryArguments::getArguments() no longer includes custom fields in Craft 5.6.0+ (craftcms/cms#16326).

Rather that update registerGqlQueries() to be consistent with how Craft defines entry queries, this PR simplifies the function to just figure out which queries are already defined by $event->queries, and only overwrite their resolver properties.

Fixes #160

[LucaDelBuono]

I'm getting this error on any query now:

"exception": "yii\\base\\ErrorException",
"message": "Undefined variable $name",
"file": "...................\RestrictionService.php",
"line": 114,

[brandonkelly]

Apologies, that’s fixed now.

[LucaDelBuono]

Works again, thank you so much for your hard work @brandonkelly !!!

[LucaDelBuono]

Can we get this merged in @jaydensmith please?

[jamesedmonston]

@brandonkelly thanks so much