Wireheader improvements to prepare for potential wire header changes

[jn9e9]

Note that the first four fields:

• magic number
• header size
• major version number
• minor version number

will always have the same width and position on every Parsec request/response header, no matter the wire protocol version. It would then make sense to either separate them in their own structure or not include them in the wireHeader structure, which will be the one that is versioned. In the Rust interface, we put the rest in its own wire_header_1_0 module to make it easy to write the logic selecting the correct wire header format. Though we did not implement that logic yet, at least we have the building blocks 😋 you have some more info here

Originally posted by @hug-dev in #28 (comment)

Also consider this comment: #28 (comment)