cardano-cli has no support for generating a DRep update certificate(18)

[gitmachtl]

$ cardano-cli version
cardano-cli 8.17.0.0 - linux-x86_64 - ghc-8.10
git rev a4a8119b59b1fbb9a69c79e1e6900e91292161e7

There is currently no (at least exposed) function to generate an update-certificate for DRep registration tag-18:

cardano-cli conway governance drep
Usage: cardano-cli conway governance drep
                                            ( key-gen
                                            | id
                                            | registration-certificate
                                            | retirement-certificate
                                            | metadata-hash
                                            )

  DRep member commands.

Available options:
  -h,--help                Show this help text

Available commands:
  key-gen                  Generate Delegate Representative verification and
                           signing keys.
  id                       Generate a drep id.
  registration-certificate Create a registration certificate.
  retirement-certificate   Create a DRep retirement certificate.
  metadata-hash            Calculate the hash of a metadata file.

CDDL:
https://github.com/IntersectMBO/cardano-ledger/blob/a596eef045d19b7dcfbb410fca8362a65ec2258e/eras/conway/impl/cddl-files/conway.cddl#L316

So please add this functionality by providing a new function update-certificate or by providing a flag in the existing registration-certificate function like --update to generate an update certificate.

@smelc

Thx!