CMake: Wrong Config Install Path

[Axel Huebl]

Hi,

As of SENSEI 4.0, the SENSEI CMake config packages are installed in the wrong location.

On Ubuntu, I find them under lib[64]/cmake instead of lib[64]/cmake/sensei, which breaks the standard CMake find_package order:
https://cmake.org/cmake/help/v3.24/command/find_package.html#config-mode-search-procedure

Note that you need to either use a more universal path above or add extra handling if you also like to support Windows.

The current bug makes development harder for WarpX devs and requires work-arounds in package managers, see e.g. spack/spack#31542

[Burlen Loring]

fixed in #80