Introduce JRL CMake Modules v2

[ahoarau]

In this PR we introduce the JRL CMake Modules v2, extracted from the repo: https://github.com/ahoarau/jrl-cmakemodules-v2

The integration on the user-side can be done as follows https://github.com/ahoarau/nanoeigenpy/blob/db692b1dbe3fff76688550048fd3004ecbd1a2d7/cmake/get-jrl-cmakemodules.cmake

find_package(jrl-cmakemodules 1.2.0 CONFIG REQUIRED)

• v1.2.0 will integrate the v2 folder, containing the new API.
• Either set an env variable JRL_CMAKEMODULES_SOURCE_DIR pointing to the jrl repo source (example $env:JRL_CMAKEMODULES_SOURCE_DIR="C:/a/jrl-cmakemodules"
• We do not intend to use both v1 and v2 in projects.

TODO:

• Port the main modules
• Test the integration in client repo (proxsuite, eigenpy, nanoeigenpy, coal)
• Figure out why gersemi still needs to re-format the new modules
• Add COMPATIBLITY_OPTION for jrl_cmake_dependent_option()
• Port tests from original repo
• Port CI from original repo
• Rewrite release.cmake in python
• Port pypa metadata

[arntanguy]

Just gave it a try with SpaceVecAlg: jrl-umi3218/SpaceVecAlg#67
There seems to be an issue with BUILDSYSTEM_TARGETS, see my comment inline.

Besides that it worked just fine. I'll keep exploring during the week.

[nim65s]

That's a lot of work 😅

I did not look into external-modules yet, but here are some comments as a starting point.