Add codec id to message formats

[cam-schultz]

Why this should be merged

Fixes #470
Updates the message formats in StakingMessages to reflect the latest iteration of ACP-77: avalanche-foundation/ACPs#135

How this works

• Adds codecID to all Warp message fields.
• Combines packRegisterSubnetValidatorMessage and packValidationInfo. packValidationInfo previously did not include the codecID and typeID in the validationID calculation. packRegisterSubnetValidatorMessage packs the full message, including the codecID and typeID.

How this was tested

forge test

How is this documented

n/a

[geoff-vball]

👍

[michaelkaplan13]

@minghinmatthewlam pointed out that it's kind of odd for the pack/unpackRegisterSubnetValidatorMessage use different message types (one the request to the P-Chain, and the other the response).

To match the updated ACP-77 spec, maybe we should go with packRegisterSubnetValidtorMessage and unpackSubnetValidatorRegistrationMessage? Not opposed to adding the request/response nomenclature otherwise either if people think that's more clear.

[michaelkaplan13]

Generally makes sense to me. The ACP-77 spec has updated these message format and defined the actual type IDs to be used, so we'll need to update them further here to be functional.

Given this PR doesn't actually match the current spec as is, I'd lean towards including those updates here, but not opposed to doing it in a follow up either.

[cam-schultz]

Generally makes sense to me. The ACP-77 spec has updated these message format and defined the actual type IDs to be used, so we'll need to update them further here to be functional.

Given this PR doesn't actually match the current spec as is, I'd lean towards including those updates here, but not opposed to doing it in a follow up either.

Given the active iteration on the spec, I've marked this PR as draft and will bring it up to date once the spec is stable.

[cam-schultz]

Closing in favor of #492