Add sniff for unsilenced deprecation warnings

[Boegie]

Resolves https://www.drupal.org/project/coder/issues/3412078

Although this could quite easily be integrated in \Drupal\Sniffs\Semantics\FunctionTriggerErrorSniff, I've opted for a separate rule. Main reason being that there are two known unsilenced deprecations already. Adding to an existing an enabled rule would break Drupal CI.