test: refactor, decouple HasReason from test framework machinery

Avoid providing the entire unit test framework dependency to tests that only
require access to the HasReason utility class.

E.g. reverselock_tests.cpp, sync_tests.cpp, util_check_tests.cpp, util_string_tests.cpp,
and script_parse_tests.cpp only require access to HasReason and nothing else.

src/test/net_tests.cpp

@@ -15,6 +15,7 @@
 #include <serialize.h>
 #include <span.h>
 #include <streams.h>
+#include <test/util/common.h>
 #include <test/util/net.h>
 #include <test/util/random.h>
 #include <test/util/setup_common.h>