make surface, and cocoa surface there own extensions

Gryphn/apis/GryphnMetal/src/metal.m

@@ -25,9 +25,11 @@ gnReturnCode initBackend(gnInstance instance, gnInstanceCreateInfo* info) {
 
     for (int i = 0; i < info->enabledExtensionCount; i++) {
         if (strcmp(info->enabledExtensions[i], "GN_EXT_surface") == 0) {
-            instance->dispatchTable.createMetalSurface = metalCreateSurface;
             instance->dispatchTable.destroySurface = metalDestroySurface;
         }
+        if (strcmp(info->enabledExtensions[i], "GN_EXT_surface_cocoa") == 0) {
+            instance->dispatchTable.createMetalSurface = metalCreateSurface;
+        }
     }
 
     return GN_SUCCESS;

main.mm

@@ -33,8 +33,9 @@ void createInstance() {
     }
     gnBackend* backends = (gnBackend*)malloc(sizeof(gnBackend) * backendCount);
     CHECK(gnGetAvaliableBackends(version, &backendCount, backends));
-    const char* extensions[1] = {
-        "GN_EXT_surface"
+    const char* extensions[2] = {
+        "GN_EXT_surface",
+        "GN_EXT_surface_cocoa"
     };
 
     gnInstanceCreateInfo createInfo = {
@@ -47,7 +48,7 @@ void createInstance() {
         },
         .enabledValidationLayerCount = 0,
         .enabledValidationLayers = nullptr,
-        .enabledExtensionCount = 1,
+        .enabledExtensionCount = 2,
         .enabledExtensions = extensions
     };
     CHECK(gnCreateInstance(&instance, &createInfo));