Consider moving the LocalizedOutboundLink component to a separate npm package

[toolness]

Reviewing JustFixNYC/who-owns-what#443 made me realize that there's a need for this handy component (see e.g. #1545 for some explanation of its usefulness) in our other codebases. It might be nice to have it be a package in our justfix-ts monorepo so they can use it.

The main wrinkle is figuring out what to do with its use of SupportedLocale, since each project will have its own concept of a supported locale. We could add it as a parameter to a generic type but that could make things really complicated, too.