[FEATURE] Add support for Structure Matching

[Starexify]

In haxe, we can use pattern matching on structures using switch statements (as documented in the Haxe Manual.

This example code from there:

var myStructure = {
  name: "haxe",
  rating: "awesome"
};
var value = switch (myStructure) {
  case {name: "haxe", rating: "poor"}:
    throw false;
  case {rating: "awesome", name: n}:
    n;
  case _:
    "no awesome language found";
}
trace(value);

would return haxe back

But in polymod this isn't supported and errors with these errors, or returns null if only the first case is used:

 ERROR  Error while executing function WorstCParser.onCreate()#0:
Tried to access "n", but it is not a valid field or method.
 ERROR  Error while executing function WorstCParser.onCreate()#0:
Tried to access "_", but it is not a valid field or method.