Add option to select language preference

[jsolly]

Context

We want to capture the user's preferred language. If they select Spanish, all of their notifications will be in Spanish.

Possible Design

A picklist.

Notes

Browsers encode the user's language into their user agent. We can pick this value up and set the language that way. If we can't find a language, maybe we use IP address and geocode it?

If we can't do that, maybe just default to English.