Add ObjectStore::put_multipart_opts

[tustvold]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Following #4984 added ObjectStore::put_opts taking a PutOptions containing a PutMode. #4999 extended this to support specifying a TagSet. #5334 proposes extending this to support broader categories of metadata.

Whilst PutMode does not apply to put_multipart, as no stores AFAIK support conditional multipart uploads, but TagSet and Attributes would be applicable to multipart uploads, as pointed out by @Xuanwo on #5431 (comment)

Describe the solution you'd like

I would propose introducing a new PutMultipartOptions and a corresponding ObjectStore::put_multipart_opts, with a default implementation of ObjectStore::put_multipart calling through with PutMultipartOptions::default().

Describe alternatives you've considered

We could not do this, however, this would create an unfortunate bifurcation in functionality between multipart and non-multipart uploads.

Additional context

[tustvold]

Going to proceed with #5458 instead