Add Ord constraint on CertVRF in VRFAlgorithm

[neilmayhew]

Description

We want to be able to store ledger predicate failures in a Set, which requires an Ord constraint. Some of these failures transitively embed VRF certs so they too need to have Ord instances.

This change adds Ord instances for the three types of VRF provided in base. It also upgrades the Eq constraint to Ord in the VRFAlgorithm class to avoid having to repeat more specific constraints in many places in the ledger codebase.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated
• All visible changes are prepended to the latest section of a CHANGELOG.md for the affected packages.
  New section is never added with the code changes. (See RELEASING.md)
• When applicable, versions are updated in .cabal and CHANGELOG.md files according to the
  versioning process.
• The version bounds in .cabal files for all affected packages are updated.
  If you change the bounds in a cabal file, that package itself must have a version increase. (See RELEASING.md)
• Self-reviewed the diff

[lehins]

Very nice.
Thank you!