Deprecate predicate inferring from class names

[flash-gordon]

Fixes dry-rb/dry-schema#335

[doriantaylor]

I tried to fire up the code that caused me to file dry-rb/dry-schema#335 and now it complains with this deprecation error but there is ostensibly no future-proof way to have a Types.Constructor(::URI) (or I suppose Types.Instance(::URI)).

Given that certain class names are invariably going to collide with the predicate registry, is there not a way that this behaviour could be scoped to the actual type itself? Consider:

URIType = Types.Constructor(URI) do |x|
  # do some stuff with x
  URI.parse(x)
end

# something like this?
URIType.ignore_predicate_test = true

(Or, to be honest, I would be perfectly happy with a built-in URI type.)