Fixes#1708
This PR focuses on evaluating the `x-amz-if-none-match` precondition header for object PUT operations. If any value other than `*` is provided, a `NotImplemented` error is returned. If `If-Match` is used together with `If-None-Match`, regardless of the value combination, a `NotImplemented` error is returned. When only `If-None-Match: *` is specified, a `PreconditionFailed` error is returned if the object already exists in `PutObject` or `CompleteMultipartUpload`; if the object does not exist, object creation is allowed.
Fixes#1709
If any precondition header is present(`If-Match`, `If-None-Match`) in `PutObject` and `CompleteMultipartUpload` and there's no object in the bucket with the given key, a `NoSuchKey` error is now returned. Previously the headers were simply ignored and new object creation was allowed.
Closes#1714
There is a `Location` field in the `CompleteMultipartUpload` result that represents the newly created object URL. This PR adds this property to the `CompleteMultipartUpload` response, generating it dynamically in either host-style or path-style format, depending on the gateway configuration.
Fixes#1710
The `If-Match` and `If-None-Match` precondition header values represent object ETags. ETags are generally quoted; however, S3 evaluates precondition headers equivalently whether the ETag is quoted or not, comparing only the underlying value and ignoring the quotes if present.
The new implementation trims quotes from the ETag in both the input precondition header and the object metadata, ensuring that comparisons are performed purely on the ETag value and are insensitive to quoting.
All the integration tests used to be in a single file, which had become large, messy, and difficult to maintain. These changes split `tests.go` into multiple files, organized by logical test groups.
