NBODY6++GPU-Beijing HIP version

This is based of the dev branch of the main version. In this version, CUDA is replaced by HIP.

Apart from that, the code should be the same as the main version.

Tested on some Chinese hardware GPU based on HIP. Compile ✅ , run ✅ .

Usage: ./configure --help, and refer to the README.md file in the main version.