Add prjxray-tools (or prjxray-tools) support

[mithro]

As part of the work in creating Project U-Ray (based on Project X-Ray) the tooling required by end users (such as FPGA RTL developers) have been split from the repo containing the fuzzers and other documentation generation tooling.

This should make it easy to package and is needed for Xilinx 7 series support (with either vpr or nextpnr).

[mithro]

https://github.com/SymbiFlow/prjuray-tools