Move GUID definitions to Protocol modules

I have deprecated GuidKind in !14 (merged).

As a follow up, move all GUID definitions to their respective protocols instead.

I can see this being done in one of the following ways:

• Just move the pub const to the new module
• Have each protocol define an associated constant called GUID
• By extension of the previous, implement a trait for protocols to require a GUID

The GUID module itself should only define the nil UUID (NULL GUID in Microsoft parlance), and potentially the new max UUID.