FAQ: document additional tools required for C/C++ development

[traversaro]

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Whenever I suggest users to use conda-forge for C/C++ development, I almost always suggest them to install the packages:

compilers cmake pkg-config make ninja meson

while this list is quite an arbitrary choice (for example, most Windows users do not actually need make, and typically only one of cmake or meson is used) I found it useful to have a simple list of packages that users need to install, without having to think too much about it, so I thought it would be useful to have it in the main conda-forge docs.

I think this is particularly useful as sometimes the reason of why you need all this packages are really far from intuitive or obvious. Some examples:

• compilers instead of cxx-compiler: A user wants to develop a C++ library with CMake, so intuitively it just installs cxx-compiler and cmake packages. If it does that, CMake may fail complaining that a C compiler is not found, as CMake always look for a C compiler unless LANGUAGES CXX is not explicitly passed to the project command invocation. And even if a user sets LANGUAGES CXX in its root CMakeLists.txt, C language support could still be used in a Find<pkg> script or in a dependency included (even transitively) via FetchContent, so it is difficult to anticipate when c-compiler is also require, and when not.
• cmake pkg-config instead of cmake: many Find<pkg>.cmake scripts, either provided by CMake or in third party projects, rely on pkg-config being available for finding projects that install .pc files. Not having pkg-config may result in enigmatic find_package(...) failures, especially for not experienced users.

I sometimes wonder if it could make sense to a build-essential meta-package similar to the similar package available in Debian, but I guess that would be a longer discussion, as a first step just adding some details in the docs seemed the easiest thing to do.

I opened this PR just encountered users on Twitter confused by how to do C/C++ dev with conda-forge (see https://x.com/sitraversaro/status/1858085950078746697), and I realized it could be convenient to have this info in conda-forge docs.