Query events by subscription filter about firefly HOT 2 OPEN

The wrinkle here, is that SubscriptionFilter applies filters as a Regular Expression, and currently we don't have support for regular expression filters in our DB semantics.

So I think the most straight forward and determinsitic way to build this feature is:

• Run the DB query without skip and limit from the API call (use our own internal skip + limit)
• Use the existing go code from the filtering that is done in the subscription to post-filter these
• Loop on the skip + limit in our internal loop, until we've fulfilled the skip + limit on the external

from firefly.

PR for this now open at #1452

from firefly.