Show tags on deleted edits through the API

Add support for viewing and filtering by tags in list=deletedrevs in the
API. This code is mostly copied from the prop=revisions code. To avoid
bug #45619 reoccuring here, no index is specified.

Change-Id: I53a1e0479bc6bafe2a1115de875548519e5b3b59
Merge "Show tags on deleted edits through the API"