Add entity resolution capability to search

To improve the quality of our search results, we need to be able to resolve entities so that we can collapse multiple entries into a single one based on a set of rules.

Business Analysis

- [x] Initial meeting of an entity resolution working group to frame the problem and explore lines of investigation

Meeting output: See comments section below.

No files, tests, or entry points are identified in the issue. Start with the comments and the entity-resolution working-group meeting output, then establish the rule set and search integration scope before implementation; done should mean duplicate entities are collapsed consistently according to agreed rules.

Written by the indexing model from the issue text.