Add orientation to encoder builder (passed on to basicinfo)

[Matthias-Fauconneau]

I'm using num-enum in sys to impl TryFrom for Orientation but you might prefer to add an enum in -rs instead with a conversion method.

[inflation]

Yes, I would prefer to not introduce another dependency for such a small change. Also, the encoding speed enum is from libjxl and could add extra validation upon usage.

I'm also including the Cargo.lock file to speed up CI and MSRV checks: https://blog.rust-lang.org/2023/08/29/committing-lockfiles.html