Make it possible to disambiguate 'familiar' names

[nonprofittechy]

Fix #857

Returns the individual's name in the most familiar form possible.

The purpose is to allow using a short version of the individual's name in an unambiguous
way in the interview. For example: referring to the child in a guardianship petition
by first name instead of "the minor". But there may be a problem if context doesn't make
it clear if you are talking about the child or their parent when they share a name.

In order, it will try to use:

• just the first name
• the first name and suffix
• the first and middle name
• the first and last name
• the full name
• the default value, e.g., "the minor", if provided
• the full name

Example usage:

Who do you want to take care of ${ children.familiar(unique_names=parents + petitioners, default="the minor") }?

[ekressmiller]

This seems like a good idea. I hadn't thought of that pitfall of using just the first name but in retrospect it's so clear!