Updates to eholdings

[bbusenius]

Changes are needed for how eholdings display. Most of these changes relate to deduped eholdings specifically.

• The heading should be changed from "Deduped Eholdings" to "Online".
• The "external link" icon should be added after all eholdings links.
• Coverage label and statement "coverage unavailable" should not be displayed for eholdings links that are triggered by a bib number (marc 928 field).
• Call number, public note, and materials specification note fields should be added to the link display.