Sealed local interfaces

[Remi Forax]

I've found a discrepancies in the current spec of sealed,
the current spec allows local sealed interface but you have no way to provide a 
sub-types apart a sealed sub interfaces.

A record or an interface is allowed to be declared inside a method,
by example, this is a valid code
  static void foo() {
    interface I {}

    record Foo() implements I {}
  }

the interface can also be sealed
  static void foo() {
    sealed interface I {}

    record Foo implements I {}
  }

but this code does not compile because Foo is a local class and a local class 
can not implement a sealed interface.

This rule was intended to not allow this kind of code
  sealed interface I {}
  
  static void foo() {
    record Foo implements I {}
  }
because the interface I is visible while Foo is not.

But we have forgotten to discuss about the case where both Foo and I are in the 
same scope.

I see two possible fixes
- disallow sealed local interfaces
- allow local class/record to implement a sealed interface if they are in the 
same scope. 

Rémi