Currently, when building cudf JNI, we specify the path to the build folder of libcudf so we can find nvcomp:

if(NOT DEFINED nvcomp_DIR)
  set(nvcomp_DIR "${CUDF_CPP_BUILD_DIR}/_deps/nvcomp-build")
endif()
rapids_find_package(nvcomp REQUIRED)

However, we only do that for nvcomp. For all other dependencies, we always pull from their sources, despite that they were already downloaded during configuring libcudf.

We should reuse the dependencies that are already downloaded, either in libcudf _deps folder or in the installed path of libcudf (if available).