Consider streams when checking for user/* contents

My `setup.php` does
```php
return [
'environment' => $environment,
'streams' => [
'schemes' => [
'user' => [
'type' => 'ReadOnlyStream',
'prefixes' => [
'' => ["user/foobar/"],
]
],
]
]
];
```

Still, `problems` does not interpolate (custom) streams and blindly checks for `user/data` instead of `user/foobar/data`etc...