Sort keys of string enums when saving in vscode

[jpike88]

Description

An extremely useful tool we enjoyed is this:

https://github.com/infctr/eslint-plugin-typescript-sort-keys/blob/master/docs/rules/string-enum.md

It's an eslint plugin, which just sorts they keys of string enums.

We have some enums which can be hundreds of keys long, and there's no practical way to sort them automatically without a tool like this