Via defining the LB_STD_VERSION_NS macro using the
target_compile_definitions().
Its name a bit inconsistent though, but looks better (in my opinion) in
C++, but doesn't look OK in a bunch of CMake configure parameters as it
conflicts with another flags (`LBSTD_VERSION_xxx` vs `LB_STD_VERSION_xxx`).

For better test cases descriptions.

For CTest statistics / grouping of similar tests.
Doctest uses the TEST_SUITE() name for CTest label or the
doctest::test_suite() decorator.