Use CMAKE_PREFIX_PATH in addition to individual <dep>_DIR #251
Description
Summary
Make use of CMAKE_PREFIX_PATH for all dependency paths.
Rationale
CMAKE_PREFIX_PATH provides a standardized centralized list of dependency paths for CMake's built-in find_* tools. It's also nice for users who are used to the convention to use this variable instead of worrying about which other variables to specify.
Description
Any path variables used for dependency finding should be appended to this list and this should be the default used for "finding".
Additional information
See https://cmake.org/cmake/help/v3.22/variable/CMAKE_PREFIX_PATH.html