PyInfra: Add tool support for Xilinx Vivado IP Catalog

[Paebbels]

Xilinx Vivado uses a new IP-XACT-based file format (*.xci) to describe IP cores in their IP catalog. PoC needs to support the extraction of source codes and generation of netlists from these files.

Note:
PoC can already handle Xilinx Core Generator files (*.xco) from Xilinx ISE.