Proto/client: add register companion key at self delegation time

What

Fix #7885 (closed)

Add the commands

octez-client register key <manager> as delegate with companion key <companion_key>

and

octez-client register key <manager> as delegate with consensus key <consensus_key> and companion key <companion_key>

Why

Better UX

How

Ctrl+c; Ctrl+v

Manually testing the MR

In sandbox mode, create some keys (delegate, some cks too, don't forget to use --sig bls for your companion key)

Use one of the above commands

After the operation has been included, observe that the keys are correctly registered, by calling the /delegates/<delegate_pkh> RPC

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