UTF8 to Any Encoder implementation

Is there anything in progress/alternative regarding the first point of the Future work paragraph of the README ?

> An encoder that accepts an arbitrary std::io::Write implementation and takes valid UTF-8 and transcodes it to a selected destination encoding. This encoder would implement std::fmt::Write.

If not, would you be open to a PR implementing such encoder ?

Start with the first point in the README's Future work paragraph and inspect the existing encoding_rs_io entry points. The work is complete when an encoder accepts any std::io::Write, transcodes valid UTF-8 to a selected destination encoding, and implements std::fmt::Write.

Written by the indexing model from the issue text.