feature: Add Conditional Write support

[Xuanwo]

Allowing users to write storage only when condition matches (or not).

[suyanhanx]

For now, like HTTP-based services, we could use if_match or if_not_modified_since as conditions.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Match https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Unmodified-Since

[Xuanwo]

Tracked at https://github.com/apache/opendal/issues/5218