Explore using `@octokit/rest` #3599

GitHub offers their own API module: https://github.com/octokit/rest.js

I've always shied away from using it due to its size, but it's worth seeing what our code would look like if we replaced our api.ts with the 1st-party module.

Would there be advantages? Would there be disadvantages other than weight? Would it still need a lot of boilerplate?

PR welcome to convert one or two api.v3 features to octokit/rest.js to evaluate it.

There's also https://github.com/octokit/graphql.js to consider and it would probably be more advantageous since they offer proper GraphQL variables