pins: allow 'ipfs pin add --name' to override name

[hacdias]

Followup of #10261.

Allowing pin add to overwrite the current set name looks slightly more involved than expected, so I decided to separate it into a different task. I set it for the current iteration. I will see if I have time to go around it.

TODO

• test that confirms ipfs pin add --name A CID && ipfs pin add --name B CID` ends up with B and not A
• if we allow for name ovveride here, we should update helptext in ipfs pin add --help, as noted here