Allow forwarding parameter attributes as Args fields attributes

[swfsql]

When an argument is generic (or is an associated type) that is bounded on serde::Deserialize (or serde::DeserializeOwned), the code generated by serde will add extra unnecessary bounds on specifically _serde::Deserialize<'de>, even when the type would already have bounds on eg. serde::DeserializeOwned.

As stated in their issue, serde-rs/serde#1296, one workaround is to attach some serde attributes that would prevent it from happening.

So for this, it should be possible to forward attributes to be attached to the fields on the Args structure definition. The best place for this is probably on the method parameters themselves.