Support for Virtex VC707

[mbelda]

Background Work

• [X] Yes, I searched the mailing list
• [X] Yes, I searched the documentation

Feature Description

I would need support for the Xilinx VC707 board. I have seen that the support for the shell is already done (or started at least). https://github.com/sifive/fpga-shells/blob/master/src/main/scala/shell/xilinx/VC707Shell.scala

So it just needs to be added to chipyard/fpga/src/main

Motivating Example

I could use the board to deploy a 16-by-16 Gemmini that does not fit in the artys that had support (and I don't have the vcu118..)