New Lookup PORO

[nimmolo]

Lookup is a new class of POROs to flexibly parse index filtering params. This was previously handled by instance methods inside Query::Modules::LookupObjects and LookupNames. Moving this to a PORO makes these lookups available to model scopes and tests, independently testable, and hopefully easier to debug.

These lookups are used in searches like "Observations by (given) Users" "Observations for (given) Projects". We can filter more than one project at a time, for example "NEMF 2023" and "NEMF 2024". Query needs the IDs, though (as would ActiveRecord), so the lookup handler makes the param format flexible for the caller. With projects, we can pass strings or ids, and Query will make sense of them. projects: ["NEMF 2024", 234]. With a users filter, the choices are instances or ids: users: [users(:mary), 4567432].

The new class Lookup is intended as a more "omnivorous" looker-upper of records. It can handle any identifiers we're likely to throw at it: a string, ID, instance, or a mixed array of any of those. The lookup_method has to be configured in the Lookup child class, because the lookup column names are different for each model.

A Lookup instance has accessor methods that return either an array of ids, instances or titles of the records matched.

fred_ids = Lookup::Users.new(["Fred", "Freddie", "Freda", "Anni Frid"]).ids

Query already has LookupObjects and LookupNames modules that do something very much like this, but they don't handle as many cases: Query param configurations handle either names+ids or instances+ids. After this PR, it will be possible to adjust Query to handle all three in all cases, allowing us to consolidate duplicative params like project/projects that make the class more confusing.

[coveralls]

coverage: 93.368% (-0.01%) from 93.38%
when pulling defe252 on nimmo-lookups-PORO
into 14e2cc0 on main.