fix: allow focal point when no sizes defined (#6397)

Allow focal points to be saved even when no imageSizes are defined.
Expands upon #6364 .

test/uploads/config.ts

@@ -198,6 +198,17 @@ export default buildConfigWithDefaults({
         staticURL: '/focal-only',
       },
     },
+    {
+      slug: 'focal-no-sizes',
+      fields: [],
+      upload: {
+        crop: false,
+        focalPoint: true,
+        mimeTypes: ['image/png', 'image/jpg', 'image/jpeg'],
+        staticDir: './focal-no-sizes',
+        staticURL: '/focal-no-sizes',
+      },
+    },
     {
       slug: mediaSlug,
       fields: [],