Draft: Env V16: use signature V3

What

update the signature version used by the latest protocol environment v16 from signature V2 to V3 that allow support of ML-DSA-44 support.

TODO:

• michelson_V1_gas handle MLDSA44 case and cost

Why

To allow ML-DSA-44 keys in the next protocol.

How

• Bump signature version to V3 in protocol environment V16
• Add a new prefix kind for signature encoding that allow to handle ML-DSA-44 big signatures.

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR