Provide citation display/download in various formats

[aaron-collier]

One of the changes coming soon from H3 is that we will only be providing a preferred citation IF the depositor has edited a custom citation. So if there is no preferred citation it will need to be structured from the individual cocina metadata. We would like to be able to offer the user the ability to see and/or download the citation in multiple formats (APA, MPA, etc...)

Note: At this point, I'm just capturing the need for this in PURL in this ticket. This will be clarified as we get closer to supporting this on the cocina/h3 side. Any lack of clarity will be addressed during planning.