Implement optional tag deletion API

[TerryHowe]

Implement optional tag deletion API.

Just a note: The tag deletion API is an optional feature in the distribution-spec, which states,

A registry MAY implement tag deletion, while others MAY allow deletion only by manifest.

To support this feature, it would need to be implemented on the underlying oras-go library side.

Originally posted by @Wwwsylvia in #1752