Give users the ability to split incorrectly merged candidates

[VirginiaDooley]

Ref #646

This is an MVP to offer users the option to split candidates that have been incorrectly merged. While this MVP does not currently use version data from past merges to present options for splitting, there is code here to do that. Instead, this offers users the attributes of a given person to keep, move or do both for a new person.

There are still several design questions in comments, absolutely no tests and I appreciate the templates are still crude. But hopefully a decent place to start!

To test, navigate to a person view, even better if it is a person with election results entered as that is the context for this feature request. Find the button in the first screenshot on the right hand column.

At the moment, I've just offered users name and gender to work with; there are outstanding questions in the code about how best to present users with available fields and what to do about required fields.

• Add a button on the person view for users to choose to split

• Present the user with a form template for selecting various properties to add to each person (1st, 2nd or both)

• Submit the previous form to the pre-split review page

• Post split confirmation page

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1205277846955833