Compiler does not fully enforce funky contract

[cpurdy]

Describe the bug
Missing compiler / verifier check for functional interface requiring all funky methods to be implemented together.

To Reproduce
Dima's test case:

    class ClassA implements Hashable {
        @Override
        static<CompileType extends ClassA> Int hashCode(CompileType value) {
            return 123;
        }
    }

Expected behavior
Compiler error stating that not all functional interface methods must be implemented / overridden together.

Additional context
https://discord.com/channels/837372142576205885/1406009322307190834/1521473507815329884