find a better way to build config IDs

Problem/Motivation

We assemble config IDs using a prefix for our module, the finder ID, and then IDs of the config entities they are derived from.

The problem is that the IDs get longer and longer, as each one has the module + finder ID prefix.

E.g.:

> $facet_id = $index->id() . '_' . $view->id();

The index ID and the View ID already both contain 'finders' in them.

Steps to reproduce

Proposed resolution

Find a better way to derive IDs.

Remaining tasks

User interface changes

API changes

Data model changes