Add copy support

[Xuanwo]

• copy inside the same operator: maybe we need a new method in Accessor?
• copy across different operators

[suyanhanx]

Will we create other copy operations? For example, copy multiple files to the target folder, or copy the entire folder.

[Xuanwo]

Will we create other copy operations? For example, copy multiple files to the target folder, or copy the entire folder.

Yes, we can add a similar feature to the copy function as we did for the remove_xxx function. However, implementing those features correctly is complex. Therefore, I will delay their implementation until users request them.

Before we do that, we can add move operation first or add more services support for copy.