Use `anymore` or some similar crate

[PoignardAzur]

The Linebender ecosystem has published the anymore vocabulary crate, which provides the AnyDebug trait. We wrote it to fill a very specific niche in Xilem and Masonry, but it's lightweight and broadly usable.

Would you consider taking a dependency on anymore and having AnyDebug implement Downcast?

We currently use anymap3 in our Masonry crate, specifically for the Properties type. One of the features we'd like would be to impl Debug for Properties, but that can only give us meaningful debug information if we use AnyDebug or something similar as the value type of our Map.

See linebender/xilem#1336 for an example implementation.

[reivilibre]

I'd be happy to accept a (optional?) dependency on anymore so AnyDebug could be used in a Map, yeah :)