[SYCL][UR][CMake] Stop creating debug library builds on Windows during release builds

[steffenlarsen]

Currently the SYCL library and its constituents build both a release build and a debug build (/MDd) on Windows, no matter what the build type is. This PR changes the build to only build in the mode specified by the CMAKE_BUILD_TYPE, meaning that packaging of release builds must build both explicitly and copy the files into the packages.

Additionally, this PR adds a new test that checks that library files in build mode all have the required postfix ("d" or "d-preview") when they link with Windows debug URCT, and the release variant if not.

[steffenlarsen]

I believe we are ready to consider this, so I've moved it to ready-for-review.

[kbenzie]

Other than use of WIN32 UR LGTM

[aelovikov-intel]

I don't think that

Currently the SYCL library and its constituents build both a release build and a debug build (/MDd) on Windows, no matter what the build type is.

is accurate. IMO, it's more like 4 configurations:

1. release build with release C/C++ runtime
2. debug build with debug C/C++ runtime
3. Optimized/possibly stripped "release-like" build with debug C/C++ runtime (and /MDd would imply -D_DEBUG and -UNDEBUG, but whatever).
4. non-optimized/non-stripped "debug-like" without MSVC's _DEBUG and linked with C/C++ runtime (most useless one).

I think before this we could ship 1 and 3, but after this I'm afraid we'd have to ship 1 and 2 and I'm really not sure if we want this. Am I missing anything?