Do not register un-implemented mime-types

[maxkadel]

Descriptive summary

Looking at the Google Search Console for a Hyku application, I see many many 501 errors for URLs that include mime-types that are not supported by any of that application's presenters.

This uses up application resources, and, if you are rate-limiting GoogleBot, the opportunity for other legitimate pages to be indexed.

Acceptance Criteria/Expected Behavior

• If no presenters implement a given mime-type, do not register that mime-type

Related work

Link to related issues or prior related work here.

Implementation notes

• Mime-types are registered in config/initializers/mime_types.rb
• There are three mime-types that are currently registered that are not implemented for Valkyrie presenters. See works_controller_behavior.rb in Hyrax. If an application has only Valkyrie works and presenters, these mime-types should not be registered.