port os functions, add testing module

src/testing/testing_main.c

@@ -0,0 +1,12 @@
+#include "core/core.h"
+#include "os/os.h"
+#include "core/core.c"
+#include "os/os.c"
+
+#include "testing.gen.c"
+
+int main() {
+    core_init();
+    run_tests();
+    return 0;
+}