Improve usage for library consumers

[JasonMarechal25]

If a consumer use pre-built binaries to use Antares lib they are expected to provide dependencies Sirius and Ortools. This patch allows consumers to define ANTARES_INSTALL_DEPS. Antares will then add the dependencies with fetch_content

• [ ] Check if ensure_X.cmake files could be FindX.cmake files
• [ ] Use CPM.cmake