Discussion- full rewrite of the training manual

Hey all!

I am starting this Issue in the hopes of having a productive conversation around rewriting the entire Training Manual to leverage one of the official GitHub SDKs.

Benefits:

* Less error prone- SDKs have the benefit of syntax completion and error checking built-in at **_writing time_**
* Consistent development and running experience- the runtimes of the SDKs handle a lot for us. I've seen many issues popping up over the last few years using this training manual along the lines of, "this works on Mac, but not on PC."
* More exposure of the official SDKs
* Truly cross-platform
* The existing scripts make a LOT of assumptions around tools that are installed... For example, I've recently run into issues due to the fact that the version of the `http` tool on my machine does not support the `-quiet` flag, which causes failures.
* Username and PAT does not always load correctly
* ...etc.

Tags for exposure:

* @githubtraining/trainers
* @amyschoen