Remove Intel FPGA support?

[j-stephan]

Intel removed FPGA support from oneAPI starting with oneAPI 2025.1: https://www.intel.com/content/www/us/en/developer/articles/release-notes/oneapi-dpcpp/2025.html

We should discuss whether we should maintain the FPGA part of the SYCL back-end.

[SimeonEhrig]

@fwyzard and it's student are on it. The student is a summer student and working on Intel FPGA support. They have a contact to Intel and will clarify how to continue.

[fwyzard]

For the time being we stay woth 2024.2 and 2025.0.

For the longer term we are following up with Altera to understand their plans.