Enable system installation of OpenRAND

[Shihab-Shahriar]

Also, renames DEVICE macro to avoid potential conflict

[palmerb4]

There are a couple issues/questions that need addressed within our CMakeLists.txt

1. Google test and benchmark are currently installed alongside OpenRAND. We only need them for testing/benchmarking, so they shouldn't be within our install interface.
2. Compilation of our tests is currently contingent on if CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR. This handles the case where OpenRAND is pulled in by an external library via fetch content but it does not handle optional enabling/disabling of tests/benchmarks/examples when compiling/installing OpenRAND directly.
3. We hard-code our CMAKE_CXX_FLAGS in ways that are non-generalizable. For example, why should we enable -fopenmp if its a requirement of our tests/benchmarks/examples but not OpenRAND itself? As well, these flags are not cross compatible between different compilers, such as -Wdouble-promotion not working for Clang.
4. Where do probdist mylib come from in target_link_libraries for TestU01?

I forked your pull request and modified OpenRAND to address 1-3. I issued a pull request to the cmake_update branch of Shihab-Shahriar/OpenRAND. If you merge, the modifications should automatically become a part of this pull request. Before you do, double check that the CI is fine. I made enabling tests, benchmarks, and examples optional, so if you want your CI to run the tests, you'd need to update the cmake build flags. I believe that will effect the CMake Configure of run-tests.yml, but I'm not familiar with github actions.

[Shihab-Shahriar]

@palmerb4 , I turned on the CI tests and updated doc. Re your q4, I largely followed this link for installing TestU01 (author of PCG).