Showcase how to integrate DB-specific functions (#201)

Augment `AdminService.Author` by 2 fields `age` and `lifetime` whose
values are computed by SQLite and HANA-specific functions.

Don't do this in bookshop directly, to keep it simple.  Instead, use
the fiori module, which also allows to integrate the fields in the UI.

Co-authored-by: Daniel <daniel.hutzel@sap.com>

fiori/app/_i18n/i18n.properties

@@ -11,6 +11,7 @@ DateOfBirth = Date of Birth
 DateOfDeath = Date of Death
 PlaceOfBirth = Place of Birth
 PlaceOfDeath = Place of Death
+Age = Age
 Authors = Authors
 Order = Order
 Orders = Orders