Fixed bug requesting non existing service from dumped frozen container

When dumping a frozen container without aliases, the method `Container::has()` will throw a *"Warning: array_key_exists() expects parameter 2 to be array, null given"* warning. It's because `PhpDumper::addAliases` returns `''` if no aliases are given. This will work for a normal constructor, because it calls the `Container::__construct` method, but the frozen constructor doesn't do that. So it requires a `$this->aliases = array();` in the constructor.

This PR fixes this bug (and adds the test). Bug is introduced in #8252 and 63367a3d5615ff65251ccee4f73223107275f65f

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -