When encoding a `network::Address` two of the fields are encoded
big-endian instead of little-endian as is done by `consensus_encode`. In
order to achieve this we have a helper function `addr_to_be` that swaps
the bytes. This function is miss-named because it is not converting to a
specific endian-ness (which implies different behaviour on machines with
different endian-ness) but is reversing the byte order irrespective of
the underlying architecture.
- Remove function `addr_to_be`
- Inline the endian-ness code when encoding an address
- Remove TODO and use `to_be_bytes` when encoding port
- Add a function for reading big-endian bytes `read_be_address`
- Use `read_be_address` when decoding `Address` and `Addrv2`
Refactor only, no logic changes. Code path is already covered by
unit tests.