Add a 'go to super method' navigation

Seems like it’s available in IntelliJ.

class A {
  void blah() {}
}

class B extends A {
  @override
  void blah() { /* cursor here */ }
}

From the cursor position, press a hotkey or execute a command, move to A.blah()

[DanTup]

Got this in #777 though I need to fix some tests before merging.

As a minor extra quality of life difference with class hierarchy, it would be nice if C extends B and B extends A to go straight from C to A if A has a method that B doesn’t override but that C does.

This works, since we wouldn’t really have anywhere to take you in B 😃

https://github.com/Dart-Code/Dart-Code/blob/ddd021b16c3991aa5313ee743bf5b8882fbc10dd/test/dart_only/commands/go_to_super_method.test.ts#L28-L38

[DanTup]

Great, thanks for the info. I’ll have a look at stashing this data somewhere so it can be access as necessary.