Tracking Issue: support content_language in opendal::options::WriteOptions

## This issue is used to track the follow-up work of the content_language option, which may include the following:
- [ ] Add content_language to metadata and capability #6470 .
- Adapt services that support this option.
- Fix the dependencies of bindings in other languages.
- Add content_language support to object_store.

Start at opendal::options::WriteOptions and trace how content_language is represented in metadata and capability. Review the affected services, bindings in other languages, and object_store integration named in the checklist. Done means the option is supported across those follow-up areas and each checklist item is resolved.

Written by the indexing model from the issue text.