Look at code coverage report, can we make it look nicer in PR comments

[TomSmith27]

Also we should group them by project so each sub project has a coverage report

[Polymeta]

Also, please, make them foldable

[Polymeta]

https://about.codecov.io/ - this looks pretty cool, also seems straightforward to setup and has nice integration. Just can't seem to set it up myself, but still looks good