new feature: copy files between operators

### Feature Description

Copying files between storage is a common use case. (The CLI tool has an implementation for instance)

### Problem and Solution

I created a copy implementation: https://github.com/sagikazarmark/opendal-util/blob/main/src/copy.rs

Would there be any interest in hosting it in this repository? I can open a PR if so.

### Additional Context

_No response_

### Are you willing to contribute to the development of this feature?

- [ ] Yes, I am willing to contribute to the development of this feature.

Start by reviewing the linked src/copy.rs implementation and the existing CLI tool implementation mentioned in the issue. Determine how the feature would fit this repository and what API and tests would define completion; the issue does not name repository files or an entry point.

Written by the indexing model from the issue text.