Thin mode

[friendlyanon]

It was suggested on Reddit that cmake-init could have a thin mode where it outputs a more lean project. The problem with this is that projects are already pretty lean and I will not drop any amount of static analysis.

The only questionable part of a generated project is maybe the documentation, which is already in a questionable state. See #58

The other things are the markdown docs at the root of the project that instruct and help remind the user how to build the project, and makes it more or less ready to be published on GitHub and tick some boxes like license, CoC, contributing guide. The BUILDING.md also explains to users of that project how to build and use it, and other related information.
This maybe can go in a lean mode. (Maybe lean mode is more like a "private project" mode?)

I have already removed the OpenCppCoverage code on the dev branch, as it's a Windows specific program and it was always there only as an example. It can still be retrieved from the git history if one wishes to reference it.

More ideas are welcome.