instead of storing modules as a struct, switch to a more "ECS" style of handling modules

src/module.c

@@ -1,6 +1,9 @@
-struct module {
+#include <stdlib.h>
-	const char *id;
+
-	void *handle;
+static void **stk_handles = NULL;
-	int (*init)(void);
+static void (**stk_inits)(void) = NULL;
-	int (*shutdown)(void);
+static void (**stk_shutdowns)(void) = NULL;
-};
+static const char **stk_ids = NULL;
+
+static size_t stk_module_count = 0;
+static size_t stk_module_capacity = 0;