`Convert Getter to Method` refactor wrong behaviour with pattern destructuring

[FMorschel]

Repro:

class C {
  int? get foo => null;
}

void f(C c) {
  if (c case C(:final foo)) {}
}

Gets refactored into:

class C {
  int? foo() => null;
}

void f(C c) {
  if (c case C(():final foo)) {}
}

The (): syntax is invalid and an unnecessary change. We should be adding () wherever the local variable is being used instead. I'll take a look at this.

FYI @bwilkerson @srawlins @DanTup