new feature: Add 'overwrite' Attribute to OpCopy and OpWrite

[miniliuke]

Feature Description

This feature would allow users to toggle the default behavior of overwriting existing files. By enabling this attribute, the system would throw an error if the file already exists, rather than overwriting it by default.

Problem and Solution

Currently, there is no way to prevent the default behavior of overwriting target files during write (creation) or copy operations. This feature would solve this issue by providing an option to control whether an existing file should be overwritten.

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.

[Xuanwo]

Thank you for bringing this up. Producing an error when the file exists is a significant feature. However, it would be better to implement it in a compatible way. Perhaps we can follow the if-match pattern and add an if-absent or if-not-exist option.

User can use this feature like:

let _ = op.write_with(path).if_absent(true).await?;

Or maybe just:

let _ = op.write_with(path).if_none_match("*").await?;