cmake: simplify showing CMake version

Move it to `CMakeLists.txt`. Drop `cmake --version` commands.

Credit to the `zlib-ng` project for the idea:
61e181c8ae/CMakeLists.txt (L7)

Closes #1203

tests/cmake/test.sh

@@ -8,8 +8,6 @@ set -u
 
 cd "$(dirname "$0")"
 
-cmake --version
-
 rm -rf bld-fetchcontent; cmake -B bld-fetchcontent -DTEST_INTEGRATION_MODE=FetchContent \
   -DFROM_GIT_REPO="${PWD}/../.." \
   -DFROM_GIT_TAG="$(git rev-parse HEAD)"