Remove KLEIDICV_HAVE_SVE2 and similar macros
Use KLEIDICV_ENABLE_SVE2 instead and propagate it from CMake to CPP with config.h.in.
Same done for KLEIDICV_HAVE_SME and KLEIDICV_HAVE_SME2.
Use KLEIDICV_ENABLE_SVE2 instead and propagate it from CMake to CPP with config.h.in.
Same done for KLEIDICV_HAVE_SME and KLEIDICV_HAVE_SME2.