Do not use find_package(glfw3) to detect if irrlicht+sdl is available

[traversaro]

Solution for #1597, alternative to #1598 . The main problem of #1598 is that it would raise a deprecation warning after robotology/ycm-cmake-modules#441 is merged. Instead, we can already avoid to use the FindGLFW3 script by passing NO_MODULE to find_package(glfw3).

[traversaro]

Cool, somehow find_package(GLFW3) failed on vcpkg, but find_package(glfw3 NO_MODULE) works fine and find glfw3, meaning that it is not a good way to detect if use or not irrlicht. Probably for the sake of the workaround, we can just enable irrlicht if conda is used.

[traversaro]

Cool, somehow find_package(GLFW3) failed on vcpkg, but find_package(glfw3 NO_MODULE) works fine and find glfw3, meaning that it is not a good way to detect if use or not irrlicht. Probably for the sake of the workaround, we can just enable irrlicht if conda is used.

Ok, I changed once again the logic, as now I do not use find_package(glfw3) at all.