removed unnecessary Settings parameter from Check::runChecks() and made Tokenizer a reference

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There was no need for the Tokenizer parameter to be a pointer as it could never be nullptr and was also dereferenced without checking first.

As a reference to the Settings was already available via the Tokenizer there was no need to pass it separately. In the production code there will only be one instance of it but in the tests we could have accidentally passed a different one.

[firewave]

The signature matched the constructor of the checks which might be created without a Tokenizer and thus need to pass the Settings by itself. That's because that constructor is used for the instance object and for a temporary object for fetching the error messages. I tried to separate/untangle this in the past but I have not been successful. I might give that a try again since it enables several interface cleanups for the checks.