Contact snippet requires 7 or more digits

## Describe the bug
A 7+ digit requirement isn't going to work for 3-1-1, or 9-1-1 or 2-1-1. We decided months ago to just leave it with the contact title as an MVP solution, but it's not a clear assumption that 3-1-1 is a phone number, especially if we list a different phone number fo rout of town users.

## URL
https://joplin.herokuapp.com/admin/snippets/contact/contact/1/

Start at the linked admin contact snippet URL and reproduce how a 3-1-1, 9-1-1, or 2-1-1 value is handled. Trace the validation and display behavior for contact titles and out-of-town phone numbers. Done means the intended short-number case is supported without obscuring the separate phone number.

Written by the indexing model from the issue text.