fix: fall back to any instead of unknown for untyped $props

[dummdidumm]

The idea was to be conservative about it, but this causes problems for people not wanting strict type checking but only a basic form of it. Falling back to any is the more pragmatic choice

#2556

@jasonlyu123 any reservations against this?

[jasonlyu123]

Ok with fallback to any. There seem to be many more people who got confused about it since the stable release is out 😅. We'll lose the ability to warn people who forgot to type the props. But at least for me that doesn't happen very often.