Use doxysaurus to publish Cxx APIs docs

[asklar]

trafficstars

last year @vmoroz had looked into using docusaurus for producing docs for the other ones, is that ready to be used on the other C++-only APIs like ReactPackageProvider etc?

filing an issue to track adding these docs

Originally posted by @asklar in https://github.com/microsoft/react-native-windows-samples/pull/719#discussion_r929456288

[chrisglein]

Work is to set up the pipelines to publish these docs automatically. Until this is fixed we have docs that are going nowhere (example: native module docs, React package provider, JSI, etc.) Script is broken, which is step one. Need to have pipeline install doxygen and then script can proceed assuming it's already there.