Support @no-named-arguments to indicate userland function does not expect named variadic arguments

[TysonAndre]

1. Variadic array type should be inferred as list<X> instead of X[]
2. Phan should warn about calls with unpacking string keys, literal named arguments, etc.

<?php
/**
 * @no-named-arguments
 * @param string|int|float ...$args
 */
function foo(string $format, ...$args) {
    printf("$format", ...$args);
}