Remove 'finders' from field labels, make finder type-specific

Problem/Motivation

e.g.

> The ‘finders channels’ field label can be set per-finder, as it’s a bundle field, defined in getChannelSelectionFieldDefinition()

Originally filed at https://github.com/localgovdrupal/localgov_finders/issues/42.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes