Fix normalization for URLs containing dash and no underscore

[romainneutron]

Symfony config normalize array keys that contains dashes and no underscore, see symfony/symfony#17129 .
We should not allow normalization on clickjacking keys in rules definition because it breaks the configuration.
For instance, the following conf:

        paths:
            '^/[a-zA-Z]+$': 'ALLOW'
            '^/': 'DENY'

becomes after normalization:

array(2) {
  ["^/[a_zA_Z]+$"]=>
  array(1) {
    ["header"]=>
    string(5) "ALLOW"
  }
  ["^/"]=>
  array(1) {
    ["header"]=>
    string(4) "DENY"
  }
}

This patch fixes this behavior

[sstok]

👍

[Seldaek]

Ah good catch thanks