Create TypeScript Best Practices and style guide

[brad-decker]

This document, which will apply to both mobile and extension (and any repository, future or present), must be ratified by members of all product teams. It should detail our best practices when using TypeScript, including configuration, code examples, etc. In addition we should include a full style guide, using our eslint configuration as the base. The eslint configuration for typescript codifies our style guide and pulling in the rules and writing examples in the style guide will help to prepare the extension for typescript refactor.

[mcmire]

The Shared Libraries team will take on an initial version of this document. It should be located in the "Standards" directory.

[mcmire]

We have begun a document for TypeScript guidelines, but we've intentionally left it incomplete for now. We will likely not have time this quarter to continue adding to it, so I am taking it out of our product backlog. That said, others are free to add more guidelines as they see fit.