[SYCL] Optionally compile all tests for Xilinx FPGA

[agozillon]

Extend the existing SYCL test infrastructure to optionally compile and execute all of the current SYCL tests (other than tests with Intel specific extensions) for Xilinx FPGA via the xocc ToolChain when make check-all is invoked.

This should be made optional/opt-in in some way as compiling all of the tests for FPGA will take a significant amount of time. This would 1) allow us to continue using the build-bot in pull requests and 2) allow people to just test the basic SYCL runtime functionality without Xilinx alterations.

Allowing the ability to choose any composition of sw emulation/hw emulation/hardware emulation would be ideal, but to start with just sw emulation would also be acceptable.

The end goal here is to have an easy to way to check all the existing tests to see what's functioning and what isn't for Xilinx FPGA's and to have a simple way to check for regressions.