local lookup changes

[iezer]

• separate config for privateCollection. This will allow both templates and components to be looked up under -components

• Make configurable whether or not the resolver should fallback to looking for a global match when passed a referrer which does not yield a local factory.

Related PRs:

• https://github.com/emberjs/ember.js/pull/15368
• https://github.com/ember-cli/ember-resolver/pull/196

[iezer]

I got rid of the allowedReferrerFallback but I think we still need the privateCollection. the definitiveCollection for a template must be routes so that template:application gets looked up in src/ui/routes/application/template. Furthermore the logic here indicates that we cannot set a namespace on the specifier and pass in an absolute referrer.

[mixonic]

I believe this is superseded by https://github.com/glimmerjs/glimmer-resolver/pull/17

[mixonic]

We took an alternative approach to this in https://github.com/glimmerjs/glimmer-resolver/pull/17. Thank you @iezer!