Add content type dependency

[sebastienros]

Invalidates any time a content item for this content type has changed, been deleted or added. To invalidate cached queries if a its results might be impacted by a change on a content item of a specific type.

/cc @paynecrl97

[paynecrl97]

Yep. It'd be good to also be able to specify which events should invalidated the cache. e.g. content-type:blogpost.created, content-type:blogpost.edited, or just content-type:blogpost.unpublished for every event.

e.g. you have a most recent blog post query, you only really need to invalidate this if a new post is published. Posts being removed or edited would be handled by the individual cache blocks around each summary display.