Merge #3098

3098: consensus: HFC now provides EpochInfo in Except monad r=nfrisby a=nfrisby

Fixes #2126. Also resolves the first draft of CAD-2713 on Jira.

This PR is a single commit; see the message.

Co-authored-by: Nicolas Frisby <[email protected]>

Author: iohk-bors[bot]