Add success printout to tests to make it easier for robert to tell if they succeeded or not

tests/basic_string.cpp

@@ -1,6 +1,9 @@
+#define LIBREXY_ENABLE_DEBUG_LEVEL 2
+
 #include "rexy/string.hpp"
 #include "rexy/allocator.hpp"
 #include "rexy/utility.hpp"
+#include "rexy/debug_print.hpp"
 
 #include <cstdlib>
 #include <cstdio>
@@ -356,4 +359,5 @@ int main(){
 	check_string_insert();
 	check_string_erase();
 	check_string_replace();
+	rexy::debug::print_succ("String test success\n");
 }

tests/format.cpp

@@ -235,5 +235,6 @@ int main(){
 	do_alt_form();
 	do_zero_pad();
 	do_type_specifiers();
+	rexy::debug::print_succ("Format test success\n");
 }