Intel: Add support for Intel LLVM-based compilers

Here is a first pass at support for the Intel LLVM-based compilers in oneAPI. It seems to work for Fortran, C, and C++ (ifx, icx, and icpx) on Linux. More testing is needed for Windows and DPC++. I did the testing before rebasing on the latest master. I see that some other changes have gone in regarding the new LLVM-based compilers for Visual Studio.

I am making the merge request while continuing to test hoping to get feedback on whether this approach looks reasonable.

The last two commits in the sequence were trying to fix some test failures due to paths with symbolic links not matching. They could probably be excluded.

Cc: @Harini
Issue: #21560, #21561 (closed)
Topic-rename: intel-llvm-compilers