Add logic to account for components with DAO links but no digitized files

[helrond]

Is your feature request related to a problem? Please describe.

Since we're likely still to be in the process of converting images on February 1st (and in order to provide as much flexibility as possible in automating image derivative creation processes) we should implement logic which looks for digitized files in addition to checking for a DAO link when determining whether or not an object is online.

Describe the solution you'd like

Add additional checking which checks for the presence of a digitized file (either by looking for a PDF, or by looking for the IIIF manifest) on page load in addition to checking the "online" key.

Additional context

There are a number of places where this will have UI/functional implications:

• View online/download buttons in RecordsDetail
• View online buttons in RecordContent
• View online buttons in MyList
• MyList parsing (some of this is tied to the Request Broker, so may be more complicated/less desirable to change)