Initial upload of fastrpc

Hi Debian backporters

I've uploaded a first version of fastrpc to trixie-backports. FastRPC is a
set of userspace services and libraries to work with DSPs on Qualcomm
platforms, it's notably used for audio or NPU offloading. While fastrpc
itself is open source, it works in conjunction with firmware binaries in
hexagon-dsp-binaries which aren't, hence it's living in contrib rather than
main.

Best
- Loïc