fix(core): add missing extension assignment

[dentiny]

Rationale for this change

Disclaimer: this issues was discovered by opus when I was leverage LLM to read through the code.

This PR adds missing extension through BufWriter single put shutdown path.
Reading through the codebase, it reads to me "attributes", "tags" and "extensions" should all be assigned for PutOptions.

Another example for multipart upload options

arrow-rs-object-store/src/buffered.rs

Lines 341 to 344 in e89f62b

	let opts = PutMultipartOptions {
	attributes: self.attributes.take().unwrap_or_default(),
	tags: self.tags.take().unwrap_or_default(),
	extensions: self.extensions.take().unwrap_or_default(),

What changes are included in this PR?

This PR passes the missing extension field to PutOption.

Are there any user-facing changes?

No

[crepererum]

Is it possible to have a regression test for this?

[dentiny]

Is it possible to have a regression test for this?

Hmmm I think it's not very straightforward; different from attributes, extensions won't appear in the response.

[dentiny]

error: explicit call to .into_iter() in function argument accepting IntoIterator
--> src/client/list.rs:120:36
|
120 | common_prefixes.extend(response.common_prefixes.into_iter());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: this parameter accepts any IntoIterator, so you don't need to call .into_iter()

hmmm I might be on an old toolchain version

[dentiny]

Hi @crepererum , sorry for the interruption and thanks for the previous reviews, I'm wondering if you mind taking another look maybe when you have some time? Thank you so much!