Handle `options.responseHeaders` when generating temporary URLs in GCS adapter

[rafiandria23]

I discovered that there's no existing implementation for options.responseHeaders when attempting to generate temporary URLs.

I only see that there's only expiresAt that's being used, I want to be able to pass responseHeaders, too. My main goal here is to be able to pass exactly the Content-Disposition header.

I can create a PR for it if you'd like.

[frankdejonge]

Happy to review a PR, I've used this for S3 for the same header.