Do not write to file system, use GitHub's APIs exclusively

[gr2m]

Today, this script does two things

1. Creates a repository and the initial pull request
2. Creates a folder locally and sets up git

I would prefer the script wouldn't interact with the fs at all, and only do step 1..

For one, not needing file access will make the script work better with deno, as we wouldn't need to ask for the file system permission. People will be less reluctant to run the script.

More importantly, I'd like this script to be run-able from a browser some day :)