Add `bytes_len()` to Params (#848)

* add len() to Params

* Rename to `len_bytes()`

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Update comment.

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Update types/src/params.rs

* Update types/src/params.rs

* Update types/src/params.rs

* Update types/src/params.rs

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>