Add Pickup Service Point token to CRUD staff slip templates

Need to add Pick-up service point token to staff slips templates (http://folio-snapshot-stable.aws.indexdata.com/settings/circulation/staffslips).

Use case: For transit slips, this is especially important since it indicates where the requestor plans to pickup the item. It may also be useful for hold slips as well.

Scenarios:

1. Scenario
   • Given create and edit mode for Staff slips (Settings > Circulation > Staff Slips)
   • When the curly braces (for inserting a new token) are clicked in the rich text editor
   • Then Pickup service point should be an available token
2. Scenario
   • Given a staff slip (e.g. Hold or Transit) is displaying in preview mode in Settings
   • When the Pickup service point token has been added
   • Then a realistic looking service point should display as an example in preview (not sure how preview currently works, is it pulling from real data?)
3. Scenario
   • Given a staff slip (e.g. Hold or Transit) contains the Pickup service point token
   • When the staff slip is previewed in the printer dialogue and/or printed
   • Then the value for the Pickup service point token (for this particular hold request or transit) should be displayed