FINERACT-1926: Fineract Asset Externalization events

- [x] Change events
- [x] Create data enricher
- [x] Core changes
- [x] Remove AbstractBusinessEventSerializer
- [x] BusinessEventSerializer.toAvroDto added and change the event serializers

fineract-avro-schemas/src/main/avro/loan/v1/LoanAccountDataV1.avsc

@@ -27,6 +27,30 @@
                 "string"
             ]
         },
+        {
+            "default": null,
+            "name": "externalOwnerId",
+            "type": [
+                "null",
+                "string"
+            ]
+        },
+        {
+            "default": null,
+            "name": "settlementDate",
+            "type": [
+                "null",
+                "string"
+            ]
+        },
+        {
+            "default": null,
+            "name": "purchasePriceRatio",
+            "type": [
+                "null",
+                "string"
+            ]
+        },
         {
             "default": null,
             "name": "status",

fineract-avro-schemas/src/main/avro/loan/v1/LoanChargeDataV1.avsc

@@ -241,6 +241,14 @@
                 "string"
             ]
         },
+        {
+            "default": null,
+            "name": "externalOwnerId",
+            "type": [
+                "null",
+                "string"
+            ]
+        },
         {
             "default": null,
             "name": "submittedOnDate",

fineract-avro-schemas/src/main/avro/loan/v1/LoanTransactionDataV1.avsc

@@ -147,6 +147,14 @@
                 "string"
             ]
         },
+        {
+            "default": null,
+            "name": "externalOwnerId",
+            "type": [
+                "null",
+                "string"
+            ]
+        },
         {
             "default": null,
             "name": "transfer",