CORE-19289 - Updated the table utxo_visible_transaction_output (#1598)

Added the column `token_priority` to the database table `utxo_visible_transaction_output`.
Created an index that uses the `token_priority` and `transaction_id` columns.

Note: 
1) Liquibase does not support the creation of an index where NULL values are last unless we write the SQL code ourselves. (See reference: https://docs.liquibase.com/change-types/create-index.html)
2) Postgres reference for creating an index with the `NULLS LAST` option: https://www.postgresql.org/docs/current/indexes-ordering.html

data/db-schema/src/main/resources/net/corda/db/schema/vnode-vault/db.changelog-master.xml

@@ -7,5 +7,6 @@
     <include file="net/corda/db/schema/vnode-vault/migration/ledger-utxo-creation-v1.0.xml"/>
     <include file="net/corda/db/schema/vnode-vault/migration/ledger-utxo-creation-v5.1.xml"/>
     <include file="net/corda/db/schema/vnode-vault/migration/ledger-utxo-creation-v5.2.xml"/>
+    <include file="net/corda/db/schema/vnode-vault/migration/ledger-utxo-creation-v5.3.xml"/>
     <include file="net/corda/db/schema/vnode-vault/migration/vnode-vault-creation-v5.1.xml"/>
 </databaseChangeLog>

data/db-schema/src/main/resources/net/corda/db/schema/vnode-vault/migration/ledger-utxo-creation-v5.3.xml

@@ -0,0 +1,22 @@
+<?xml version="1.1" encoding="UTF-8" standalone="no"?>
+<databaseChangeLog xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
+                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                   xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-4.3.xsd">
+
+    <changeSet author="R3.Corda" id="ledger-utxo-creation-v5.3">
+
+        <addColumn tableName="utxo_visible_transaction_output">
+            <column name="token_priority" type="BIGINT">
+                <constraints nullable="true"/>
+            </column>
+        </addColumn>
+
+        <createIndex indexName="utxo_visible_transaction_output_token_priority_tx_id_idx"
+                     tableName="utxo_visible_transaction_output">
+            <column name="token_priority"/>
+            <column name="transaction_id"/>
+        </createIndex>
+
+    </changeSet>
+
+</databaseChangeLog>