(WIP) n+1 query insight.

- [x] Simple identifier

Presently, if there are 5 or more queries in a given list of the form `SELECT 'foos'.* FROM 'foos' WHERE 'foos'.'id' = 13 LIMIT 1`, that table is considered to be doing an n+1 query with those queries as the n.

- [ ] Setup insight; should link to eager loading docs / short tutorial

- [ ] More robust identifier