Fixes#1643
`GetBucketLocation` in S3 returns empty `LocationConstraint` if the bucket is in the `us-east-1` region. This fix returns empty `LocationConstraint` if the gateway region is `us-east-1`.
GetBucketLocation is being deprecated by AWS, but is still used
by some clients. We don't need any backend handlers for this since
the region is managed by the frontend. All we need is to test for
bucket existence, so we can use HeadBucket for this.
Fixes#1499
Closes#1454
Adds the implementation of [S3 GetBucketPolicyStatus action](https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetBucketPolicyStatus.html). The implementation goes to front-end. Front-End loads the bucket policy and checks if it grants public access to all users.
A bucket policy document `is public` only when `Principal` contains `*`(all users): only when it grants access to `ALL` users.
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.
