Fixes#1486
* Adds the `Access-Control-Allow-Headers` response header to CORS responses for both **OPTIONS preflight requests** and any request containing an `Origin` header.
* The `Access-Control-Allow-Headers` response includes only the headers specified in the `Access-Control-Request-Headers` request header, always returned in lowercase.
* Fixes an issue with allow headers comparison in cors evaluation by making it case-insensitive.
* Adds missing unit tests for the **OPTIONS controller**.
Closes#1003
**Changes Introduced:**
1. **S3 Bucket CORS Actions**
* Implemented the following S3 bucket CORS APIs:
* `PutBucketCors` – Configure CORS rules for a bucket.
* `GetBucketCors` – Retrieve the current CORS configuration for a bucket.
* `DeleteBucketCors` – Remove CORS configuration from a bucket.
2. **CORS Preflight Handling**
* Added an `OPTIONS` endpoint to handle browser preflight requests.
* The endpoint evaluates incoming requests against bucket CORS rules and returns the appropriate `Access-Control-*` headers.
3. **CORS Middleware**
* Implemented middleware that:
* Checks if a bucket has CORS configured.
* Detects the `Origin` header in the request.
* Adds the necessary `Access-Control-*` headers to the response when the request matches the bucket CORS configuration.