Renamed test files to match pattern from src

Also, started setup for testing do_remove and introduced a bit of shorthand macros.

src/test/test.act.item.h

@@ -0,0 +1,10 @@
+#include "testrunner.h"
+
+#ifndef TEST_ACT_ITEM_H
+#define TEST_ACT_ITEM_H
+
+extern MunitTest act_item_c_tests[];
+
+UNIT_TEST(test_do_remove);
+
+#endif