Spike: CIRC-441 - Delivery requests: support tokens for delivery slip

CIRC-441: [Spike] Delivery requests: support tokens for delivery slipClosed

The goal of the spike is to investigate the process of adding new tokens to delivery slips

1. How existing tokens are added to delivery slip:

"POST circulation/check-in-by-barcode" endpoint returns "staffSlipContext" attributes in response:

 "staffSlipContext": {
    "item": {
      "title": "Bridget Jones's Baby: the diaries",
      "barcode": "453987605438",
      "status": "In transit",
      "primaryContributor": null,
      "allContributors": "Fielding, Helen",
      "callNumber": "PR6056.I4588 B749 2016",
      "callNumberPrefix": null,
      "callNumberSuffix": null,
      "enumeration": null,
      "volume": null,
      "chronology": null,
      "yearCaption": "",
      "materialType": "book",
      "loanType": "Course reserves",
      "copy": "Copy 1",
      "numberOfPieces": "1",
      "descriptionOfPieces": null,
      "effectiveLocationSpecific": "Main Library",
      "effectiveLocationLibrary": "Datalogisk Institut",
      "effectiveLocationCampus": "City Campus",
      "effectiveLocationInstitution": "Københavns Universitet",
      "fromServicePoint": "Online",
      "toServicePoint": "Circ Desk 1"
    },
    "request": {
      "requestID": "be0355f5-6920-4065-8e4f-619c54de6891",
      "servicePointPickup": "Circ Desk 1"
    },
    "requester": {
      "firstName": "Penelope",
      "lastName": "Feil",
      "middleName": "Myrna",
      "barcode": "109322966933845"
    }
  }

UI uses this object to replace delivery slip tokens with data when printing delivery slip.

mod-circulation constructs staffSlipContext in method TemplateContextUtil#createCheckInContext by using available data (data is stored in object CheckInProcessRecords).

Before constructing staffSlipContext mod-circulation retrieves all necessary data by making calls to other services in CheckInByBarcodeResource#checkin.

2. How to add new slip tokens

If data for new token is already available in CheckInProcessRecords then we just need to transfer it to staffSlipContext in TemplateContextUtil#createCheckInContext.

If data is not available then we need to retrieve it from corresponding service, store it in CheckInProcessRecords, and then add it to staffSlipContext in TemplateContextUtil#createCheckInContext