refactor: consolidate per-test subdirectories into flat test/api structure with merged returns and value files

test/api/returns.c

@@ -0,0 +1,39 @@
+#include <string.h>
+
+#include "returns.h"
+
+static void implicitNull(WrenVM* vm)
+{
+  // Do nothing.
+}
+
+static void returnInt(WrenVM* vm)
+{
+  wrenReturnDouble(vm, 123456);
+}
+
+static void returnFloat(WrenVM* vm)
+{
+  wrenReturnDouble(vm, 123.456);
+}
+
+static void returnTrue(WrenVM* vm)
+{
+  wrenReturnBool(vm, true);
+}
+
+static void returnFalse(WrenVM* vm)
+{
+  wrenReturnBool(vm, false);
+}
+
+WrenForeignMethodFn returnsBindForeign(const char* signature)
+{
+  if (strcmp(signature, "static Api.implicitNull") == 0) return implicitNull;
+  if (strcmp(signature, "static Api.returnInt") == 0) return returnInt;
+  if (strcmp(signature, "static Api.returnFloat") == 0) return returnFloat;
+  if (strcmp(signature, "static Api.returnTrue") == 0) return returnTrue;
+  if (strcmp(signature, "static Api.returnFalse") == 0) return returnFalse;
+
+  return NULL;
+}