test: Split overly large util_tests.cpp file

Author: MacroFake

src/Makefile.test.include

@@ -66,6 +66,7 @@ BITCOIN_TESTS =\
   test/addrman_tests.cpp \
   test/allocator_tests.cpp \
   test/amount_tests.cpp \
+  test/argsman_tests.cpp \
   test/arith_uint256_tests.cpp \
   test/banman_tests.cpp \
   test/base32_tests.cpp \