add third_party folder

third_party/CMakeLists.txt

+ginkgo_add_subdirectory(Ginkgo ginkgo)
+set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}" PARENT_SCOPE)

third_party/ginkgo/CMakeLists.txt

+# TODO pass flags from main CMAKE file
+ginkgo_load_git_package(ginkgo_external
+  "https://github.com/ginkgo-project/ginkgo.git"
+  "develop"
+  "-DGINKGO_BUILD_CUDA=off" "-DGINKGO_BUILD_HIP=off"
+  "-DGINKGO_BUILD_OMP=off" "-DGINKGO_BUILD_TESTS=off"
+  "-DGINKGO_BUILD_EXAMPLES=off" "-DGINKGO_BUILD_BENCHMARKS=off"
+  "-DGINKGO_BUILD_REFERENCE=on" "-DCMAKE_BUILD_TYPE=Release"
+  "-DGINKGO_BUILD_HWLOC=off"
+  "-DCMAKE_INSTALL_PREFIX=install" "-DBUILD_SHARED_LIBS=on"
+  )