I/O should be on plain JS types where possible

[mitschabaude]

Currently, interaction with Credentials, Presentations etc always requires you use o1js types. This is inconvenient and makes the library feel less like a "standard". Input values should be numbers, booleans, bytes, strings, bigints and not Field, Bool, Bytes, PublicKey etc.

Changing the implementation to do this is not hard because we have fromValue() / toValue() on every provable type which performs exactly this conversion. The only challenge is that it requires a rewrite of almost all types to also represent the "value" types (sometimes it might be enough to only represent the value types and skip the provable types)