Handle merging people

[fpagnoux]

@mprat I think this feature has been broken for a while on ui-v1, so I couldn't test it to figure out exactly what it does.
Is the idea that we let the logged in desk worker pick which affiliation / name / primary email they want to use for the new merged person profile?

[mprat]

I was just about to comment here - I had started fixing this while I was doing the implementation of the auth API for DavidCain back in September (see my WIP CR here: https://github.com/mitoc/gear-db-django/pull/347) but it exposed some issues, which is why I shifted to the model cleanup.

I'd recommend holding off on this for a little bit until the other WIP CRs land and we can focus on this one. The model cleanup CR needs to be merged first since the fixes there will enable a robust solution here.

Edited: blocked by https://github.com/mitoc/gear-db-django/issues/240

[fpagnoux]

That works for me!