Provide real implementation for AssemblySymbol.RuntimeSupportsStaticAbstractMembersInInterfaces

[AlekseyTs]

        /// <summary>
        /// Figure out if the target runtime supports static abstract members in interfaces.
        /// </summary>
        internal bool RuntimeSupportsStaticAbstractMembersInInterfaces
        {
            // PROTOTYPE(StaticAbstractMembersInInterfaces): Implement the actual check, this is a temporary stub. 
            get => RuntimeSupportsDefaultInterfaceImplementation;
        }