Refactor: validation functions

lib/common/cmp_entity.c

lib/common/cmp_support.c

lib/common/cmp_support.h

lib/decompress/decmp.c

lib/icu_compress/cmp_icu.c

lib/rdcu_compress/cmp_rdcu_cfg.c

programs/cmp_guess.c

programs/header_pars.c

test/cmp_icu/test_cmp_icu.c

test/decmp/test_decmp.c