VS: Fix detecting icx.exe with Intel Compiler toolsets newer than 2021

The logic added by commit 7808cbd6 (CMakeDetermineCompilerId: support
Intel DPC++ compiler toolset for VS gen, 2020-12-06, v3.20.0-rc1~330^2)
matches a specific toolset known to be the `icx.exe` compiler, and
assumes all other Intel C++ compilers (that are not DPC++) must be
`icl.exe`.

Since `icx.exe` is officially replacing `icl.exe`, use a regex that
matches the now-fixed set of toolsets known to use `icl.exe`.  Any other
Intel C++ compiler will be assumed to be `icx.exe`.

Signed-off-by: William R. Dieter <william.r.dieter@intel.com>
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