Fixes#1809Fixes#1806Fixes#1804Fixes#1794
This PR focuses on correcting so-called "list-limiter" parsing and validation. The affected limiters include: `max-keys`, `max-uploads`, `max-parts`, `max-buckets`, `max-uploads` and `part-number-marker`. When a limiter value is outside the integer range, a specific `InvalidArgument` error is now returned. If the value is a valid integer but negative, a different `InvalidArgument` error is produced.
`max-buckets` has its own validation rules: completely invalid values and values outside the allowed range (`1 <= input <= 10000`) return distinct errors. For `ListObjectVersions`, negative `max-keys` values follow S3’s special-case behavior and return a different `InvalidArgument` error message.
Additionally, `GetObjectAttributes` now follows S3 semantics for `x-amz-max-parts`: S3 ignores invalid values, so the gateway now matches that behavior.
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.
