Add Reconciliation API support for Archived Resources

[anjackson]

As an additional mode of integration, and covering much of the utility of the now broken Google Sheets Add On, we could support OpenRefine Reconciliation (see API spec).

Starting with Archived Resources a.k.a. Mementos, users could pass in URLs and an optional target time, and this would be matched against our CDX. Later, this could be extended to cover other web archives, or cover other entities like Host or Target records. e.g. which Target does this URL belong too?

n.b. Can be manually tested using https://reconciliation-api.github.io/testbench/