ExternalMediaLinkWrapper should produce links to all subjects

[mbergen]

Is your feature request related to a problem? Please describe.
The EMLWrapper that produces the display of EMLs on Data pages currently does not link to the subject(s).
This means these pages are not targeted by purge runs based on links, which are frequent on page moves due to ID changes.

Describe the solution you'd like
The EMLWrapper should create wikilinks to all subjects, events, and authors.

Describe alternatives you've considered

Additional context