[comm-lib][blob-client] Add support for removing holders by tags

Summary:
In D13646 and D13647 a support for removing holders by tag was added. This diff adds support for this feature in BlobServiceClient.
Added some convenience conversion traits.

Depends on D13647

Test Plan: Same as D13644 but also used tagged holders

Reviewers: kamil, varun, will

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13648