Intel oneAPI 2023.0 added the icpx compiler front-end on Windows.
It uses a GNU-like command-line, and is not yet supported by CMake.
Avoid finding icpx as the CXX compiler on Windows until support
is added.
Original Description
This works around #24266 (closed) by first looking for icx on Windows before icpx. This allows if someday oneAPI Windows decides to only have icpx. This also retains current MSVC-like driver default for those user projects relying on this default.
A long-term preference by me would be for CMake to also support icpx on Windows (perhaps !8032 (closed)), but this maintaining of icx driver default on Windows is also important.
The second commit documents which compiler drivers are supported.
Fixes: #24266 (closed)
Issue: #24314
Backport: release
Topic-rename: IntelLLVM-no-icpx-on-Windows