Allow for...of loops

[stevehanson]

This rule originally comes from the Airbnb ruleset. These were restricted by Airbnb because browser support was lacking in 2018. Browser support for for...of is now at 97%. Additionally, not all of our users are writing for the browser. Finally, for...of loops are the simplest way to loop through arrays asynchronously in sequence:

// this works, but .forEach and for...in do not
for await (const item of items) {
  await doSomething(item);
}

Similarly, this PR allows the use of continue statements. We often encourage early returns in methods, and to me continue is a similar concept, but in the context of a loop. I don't see a need to be opinionated about its usage.

https://caniuse.com/?search=for...of