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_de.properties

@@ -6,6 +6,7 @@ Authors = Autoren
 Author = Autor
 AuthorID = ID des Autors
 AuthorName = Name des Autors
+Age = Alter
 Name = Name
 Stock = Bestand
 Order = Bestellung