Add a wiki config snippet parsing test

[YaLTeR]

All config snippets on the wiki are deliberately written in such a way that you can call Config::parse() on them and it must parse successfully. Add a test that finds all config snippets in the wiki/ folder and ensures that they parse successfully.

Will need some way to either mark snippets that need to be tested, or to mark snippets that need to be skipped. Because not every code block there is a config snippet (though most are), and not every code block is even KDL.

[thepragmaticmero]

Wow this YaLTeR guy really likes to open issues, really active huh~, the dude should become a main maintainer or something.