Implement roundtrip encoding property test for Messages from random bytes

[jvff]

Motivation

It's important to ensure that incoming random bytes from the network do not cause Zebra to misbehave or crash. Having a test that tries to decode a Message from a random byte array is one step in that direction.

The idea would be to write a proptest that:

1. Given as input a random vector of bytes, with a size that varies between 0..=MAX_PROTOCOL_MESSAGE_LEN;
2. Creates Codec instance that is used to try to decode a Message from those random bytes;
3. Based on parts of the input bytes, asserts that the proper Message variant was decoded, or that the appropriate error was returned;
4. Re-encodes the decoded Message (if available) and checks that the resulting bytes are the same as those in the input

This test could also become some sort of fuzzing test.

Related Work

There is a similar test for serialization of InventoryHash that was implemented in #2446.