Improve type-safety for Identity arguments in ockam_command

[SanjoDeundiak]

We have multiple places where we accept Identity change history as a hex encoded string like here or here (there may be more places like that). It would be great to have a value_parser that would validate and decode that argument to ChangeHistory type

[Nathy-bajo]

Hey @SanjoDeundiak

I'd love to work on this and drop a PR.

[etorreborre]

@Nathy-bajo that's awesome, all yours. Please let us know if your have any questions as you explore. You can also ask questions on the contributors discord https://discord.gg/RAbjRr3kds

[Nathy-bajo]

Hey @etorreborre so sorry for the late response. I just dropped a PR for the fix.
Please can you help check on it?

[etorreborre]

Sure, but I can't find you PR: https://github.com/build-trust/ockam/pulls/nathy-bajo

[Nathy-bajo]

Sure, but I can't find you PR: https://github.com/build-trust/ockam/pulls/nathy-bajo

This is the link.

#8365

[Nathy-bajo]

@etorreborre Please can you review it so I'll know if changes might still be needed