We never plan to extend a model, and value composition over inheritance. We need to add the AllowDynamicProperties warning to prevent PHPStan errors that arise with pivot relations (https://www.github.com/larastan/larastan/issues/2256).
We've been mostly relying on the 3rd party xss cleaner to make sure user submitted content is clean. This PR fixes up any leftover holes in the bbcode parser that allow xss vulnerabilities, and as a result, the 3rd party library isn't needed anymore. It cleans responsibly by first, running `htmlspecialchars()` over the content, followed by sanitizing the untrusted urls and whitelisting their protocol.