Fixes#1751
When an object lock–related operation is performed on an object in a bucket where Object Lock is not enabled, an `InvalidRequest` error is returned; however, the error message differs for some actions. This PR introduces a new error, `ErrMissingObjectLockConfigurationNoSpaces`, for `PutObject`, `CopyObject`, and `CreateMultipartUpload` to maintain compatibility with S3 in terms of the error message. It also adds the missing integration tests for these actions.
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.
