MODINV-1307 Add sourceUri field to Instance (#418)

(cherry picked from commit e7104be)

Author: KaterynaSenchenko

ramls/instance.json

@@ -19,6 +19,10 @@
       "type": "string",
       "description": "The human readable ID, also called eye readable ID. A system-assigned sequential ID which maps to the Instance ID"
     },
+    "sourceUri": {
+      "type": "string",
+      "description": "A remote URI uniquely identifying the source of the instance"
+    },
     "source": {
       "type": "string",
       "description": "The metadata source and its format of the underlying record to the instance record. (e.g. FOLIO if it's a record created in Inventory;  MARC if it's a MARC record created in MARCcat or EPKB if it's a record coming from eHoldings)"