Fix leftover configure placeholders in cutlass/version.h

[VaggelisGian]

Fixes #3472

getVersionString() and getGitRevision() in include/cutlass/version.h returned the literal strings @CUTLASS_VERSION@ and @CUTLASS_REVISION@. Those were left behind when the configure_file step for version.h was dropped in 3.4.1 (bbe579a); only cmake/version_extended.h.in is generated, so nothing ever substituted them, and even a full CMake build prints CUTLASS @CUTLASS_VERSION@ in the profiler banner (tools/profiler/src/options.cu).

This builds getVersionString() from the CUTLASS_MAJOR/MINOR/PATCH macros and lets getGitRevision() return CUTLASS_REVISION, which is empty by default and supplied by version_extended.h under CUTLASS_VERSIONS_GENERATED. The build-number suffix behavior is unchanged.

Behavior note: the profiler banner changes from CUTLASS @CUTLASS_VERSION@ ... commit @CUTLASS_REVISION@ to CUTLASS 4.7.0, with the commit clause printed only when a real revision exists. Nothing in-tree parses the old string.

Adds test/unit/core/version.cu (3 tests) registered in test/unit/core/CMakeLists.txt.

Test Plan:

$ docker run --rm -v .../cutlass:/src:ro nvidia/cuda:12.8.1-devel-ubuntu22.04 \
    g++ -std=c++17 -I/src/include host_check.cpp && ./host_check
  unfixed header: getVersionString=@CUTLASS_VERSION@
                  getGitRevision=@CUTLASS_REVISION@   -> 4 assertion failures
  fixed header:   getVersionString=4.7.0 getGitRevision=    -> 0 failures

$ docker run --rm nvidia/cuda:12.8.1-devel-ubuntu22.04   # nvcc V12.8.93 + googletest
$ nvcc -std=c++17 -I<include> -I<gtest include> -c test/unit/core/version.cu ...
$ g++ version.o libgtest.a libgtest_main.a -lcudart -o vt && ./vt
[==========] 3 tests from 1 test suite ran. (1 ms total)
[  PASSED  ] 3 tests.

Both configurations were also compiled with MSVC against a simulated generated version_extended.h: defaults give "4.7.0"/"", generated gives "4.7.0.5"/"abc123".