Add type reference support to interface builders

[dondonz]

Fixes #2546.

An interface (or object) can contain a type reference to itself. The referenced type is replaced with the real type object when the schema is built.

This PR adds support for type references in GraphQLInterfaceType builders, making these equivalent to builders in GraphQLObjectType.

[dondonz]

Shifting this down to be adjacent to the other withInterface method

[bbakerman]

See the comments on how to avoid a breaking change

[bbakerman]

This is an API breaking change - albeit a low likelyhood one - but a breaks a break so if we can NOT do it - let not do it.

This can be rewritten like this to avoid the breaking change

        public Builder replaceInterfaces(List<GraphQLInterfaceType> interfaces) {
            return replaceInterfacesOrReferences(interfaces);
        }

        public Builder replaceInterfacesOrReferences(List<? extends GraphQLNamedOutputType> interfacesOrReferences) {

and then up above you can change the impl to be

    public GraphQLInterfaceType withNewChildren(SchemaElementChildrenContainer newChildren) {
        return transform(builder ->
                builder.replaceDirectives(newChildren.getChildren(CHILD_DIRECTIVES))
                        .replaceFields(newChildren.getChildren(CHILD_FIELD_DEFINITIONS))
                        .replaceInterfacesOrReferences(newChildren.getChildren(CHILD_INTERFACES))
        );
    }

[dondonz]

Add for completeness