Generate a separate field for each value of /mods/titleInfo/@displayLabel in an exhibit

[caaster]

Story:
Titles may have specific display labels associated with them that provide important context for understanding their relation to the object. Exhibit curators would like to display these labels to their users so that they may better understand this context.

Acceptance criteria:
A separate display field should be available for each value of /mods/titleInfo/@displayLabel appearing in the exhibit metadata, labeled with the displayLabel value.

[blalbrit]

Also see #722

[blalbrit]

@caaster - is there a non-Parker fixture object for this?

[mejackreed]

Work may have been done here: #722

I think this may be done, but we may just need to rename a title field manuscript_titles_ssim to something more generic?