add `DefaultWork.inspect` method for console output on models
add `DefaultWork.inspect` method for console output on models

Wings models generated AF models used to show output like
 `#<Class:0x00005579fb5a39b0>:0x00005579fb5a3a00>` when printed to the
 console. By adding a class-level `.inspect` and `.to_s` method, we can have
 nicer console output, both for the instances themselves and when outputting an
 ancestor chain. This should make debugging a bit nicer.

looking at doing this with some other classes and modules constructed with the
Class/Module Builder pattern, as
well. cf. https://dejimata.com/2017/5/20/the-ruby-module-builder-pattern#note-8

samvera/hyrax,samvera/hyrax,samvera/hyrax,samvera/hyrax