fix(s3): add missing content write content disposition capability

[dentiny]

Rationale for this change

S3 supports content disposition as part of the PUT request: https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutObject.html#API_PutObject_RequestSyntax

S3 requests already fill in corresponding header here:

opendal/core/services/s3/src/core.rs

Lines 305 to 307 in 4ea60b0

	if let Some(pos) = args.content_disposition() {
	req = req.header(CONTENT_DISPOSITION, pos)
	}

Before this fix, I think capability check layer validation will fail

opendal/core/layers/capability-check/src/lib.rs

Line 138 in 4ea60b0

if !capability.write_with_content_disposition && args.content_disposition().is_some() {

What changes are included in this PR?

Declare S3 backend supports content disposition for write operations.

Are there any user-facing changes?

No

AI Usage Statement

Opus 4.6 helped me found the missing capability declaration.

[Xuanwo]

Thank yoU!