Implement rkyv related traits

[ureeves]

Describe what you want implemented
rkyv related traits should be implemented for at least Proof to allow for passing them through the host/VM boundary.

Describe "Why" this is needed
This is necessary to be able to pass these structures to a smart contract running on the virtual machine.

Describe alternatives you've considered
N/A

Additional context
The job of serialization and de-serialization used to be performed by canonical. Due to the increased costs it entailed, we decided to architect the new VM to allow rkyvable used as transaction arguments.