1. Deprecating the `write_one` function
Semantically, this function is a composition of `write_with_len_prefix` and
`io.close()`. This represents a footgun because the `close` functionality is
not obvious and only mentioned in the docs. Using this function multiple times
on a single substream will produces hard to debug behaviour.
2. Deprecating `read_one` and `write_with_len_prefix` functions
3. Introducing `write_length_prefixed` and `read_length_prefixed`
- These functions are symmetric and do exactly what you would expect, just
writing to the socket without closing
- They also have a symmetric interface (no more custom errors, just `io::Error`)
Co-authored-by: Max Inden <mail@max-inden.de>
