Better types and minor refactor/cleanup

[TheLeoP]

Describe what this PR does / why we need it

I want to contribute more to the codebase, but it's a bit daunting without knowing it. Type annotations make it easier and more manageable. But, A lot of the types come from the Github API, so I also added a script to generate them from the Graphlq schema definition (and a the generated file). I didn't know Github also had a REST API before this PR, so those types may need to wait for now :p

Does this pull request fix one issue?

NONE

Describe how you did it

Used the Grahpql specificacion to generate LuaCAT annotations for the Github Grapgql schema. I used those types to better type (and caught a couple of error while doing it) some parts of the codebase

Describe how to verify it

I think I shouldn't have change the behavior of the plugin, but something may have slipped through my refactors. I guess the test should catch it if it happened

Special notes for reviews

Ignore the huge line count, it's mostly because of the huge generate file with the type definitions.

The script on scripts/generate_gh_types.lua needs to be run from within Neovim by doing :source with that file opened. It'll generate the file ./lua/octo/_meta/gh.lua

Checklist

• Passing tests and linting standards
• Documentation updates in README.md and doc/octo.txt