Ability to assign Custom domain to Storage buckets

### 🔖 Enhancement description The goal here is to have a custom domain per bucket and not have to use the default Appwrite URL. It’s like Cloudflare R2, when creating a bucket, you can assign a custom URL to it. Example Flow: Create Bucket Assign Custom Domain to this bucket: {enter your custom domain} How Files will look: api.example.com/buckets/<bucket_id>/files/<filename> ### 🎤 Pitch This enhancement will allow developers to serve assets directly from their own branded domains, improving both SEO and brand consistency. It also reduces reliance on the default Appwrite URL structure, making it easier to integrate. Improved Branding: Allows users to keep their storage URLs consistent with their primary domain. Better Caching: Makes it easier to put a custom CDN in front of the storage bucket. Flexibility: Matches features offered by other platforms like Cloudflare R2 or AWS S3. ### 👀 Have you spent some time to check if this issue has been raised before? - [x] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [x] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)