refactor(dependency): OCaml -> 4.12, redux

[zbaylin]

Retrying #3536

[bryphe]

Thanks @zbaylin ! Tested locally on Windows - haven't been able to reproduce a crash 🤞

[zbaylin]

Awesome @bryphe! I've been bumping up against that unqualified-id error which has prevented me from doing any development on Oni, so this should free me up again!

[bryphe]

Weird, looks the CentOS failure might be related to the prebuilt DLLs:

info install 0.6.10 (using package.json)
error unable to fetch esy-skia@github:revery-ui/esy-skia#6106223:
                                                                   source: github:revery-ui/esy-skia#6106223
                                                                   error: 
                                                                   error: command failed: 'git' '-C' '/oni2/_esy/default/tmp/esy-fc9118' 'checkout' '6106223'
                                                                   stderr:
                                                                            error: Your local changes to the following files would be overwritten by checkout:
                                                                            	prebuilt/windows/skia.dll
                                                                            Please commit your changes or stash them before you switch branches.
                                                                            Aborting
                                                                            
                                                                   stdout:
                                                                            
                                                                    fetching dist: github:revery-ui/esy-skia#6106223
error: installation error
  fetching esy-skia@github:revery-ui/esy-skia#6106223

https://dev.azure.com/onivim/oni2/_build/results?buildId=16714&view=logs&j=e3ae384d-e199-50c7-2cb4-9ce0785e7448&t=575416f9-89fc-5369-7933-ebe25f02131f&l=25