Alter table fails when adding a virtual column [DBZ-9028]

Migrated from [DBZ-9028](https://issues.redhat.com/browse/DBZ-9028)

When specifying an {{ALTER TABLE}} statement on Oracle that adds a virtual column, the Oracle parser fails with the following error:

{noformat}
org.apache.kafka.connect.errors.ConnectException: An exception occurred in the change event producer. This connector will be stopped.
at io.debezium.pipeline.ErrorHandler.setProducerThrowable(ErrorHandler.java:67)
at io.debezium.connector.oracle.logminer.LogMinerStreamingChangeEventSource.execute(LogMinerStreamingChangeEventSource.java:264)
at io.debezium.connector.oracle.logminer.LogMinerStreamingChangeEventSource.execute(LogMinerStreamingChangeEventSource.java:62)
at io.debezium.pipeline.ChangeEventSourceCoordinator.streamEvents(ChangeEventSourceCoordinator.java:324)
at io.debezium.pipeline.ChangeEventSourceCoordinator.executeChangeEventSources(ChangeEventSourceCoordinator.java:203)
at io.debezium.pipeline.ChangeEventSourceCoordinator.lambda$start$0(ChangeEventSourceCoordinator.java:143)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:842)
Caused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
at java.base/java.util.Objects.checkIndex(Objects.java:359)
at java.base/java.util.ArrayList.get(ArrayList.java:427)
at io.debezium.connector.oracle.antlr.listener.AlterTableParserListener.lambda$enterAdd_column_clause$2(AlterTableParserListener.java:116)
at io.debezium.connector.oracle.antlr.OracleDdlParser.runIfNotNull(OracleDdlParser.java:164)
at io.debezium.connector.oracle.antlr.listener.AlterTableParserListener.enterAdd_column_clause(AlterTableParserListener.java:108)
at io.debezium.ddl.parser.oracle.generated.PlSqlParser$Add_column_clauseContext.enterRule(PlSqlParser.java)
at io.debezium.antlr.ProxyParseTreeListenerUtil.delegateEnterRule(ProxyParseTreeListenerUtil.java:46)
at io.debezium.connector.oracle.antlr.listener.OracleDdlParserListener.enterEveryRule(OracleDdlParserListener.java:48)
at org.antlr.v4.runtime.tree.ParseTreeWalker.enterRule(ParseTreeWalker.java:49)
at org.antlr.v4.runtime.tree.ParseTreeWalker.walk(ParseTreeWalker.java:33)
at org.antlr.v4.runtime.tree.ParseTreeWalker.walk(ParseTreeWalker.java:36)
at org.antlr.v4.runtime.tree.ParseTreeWalker.walk(ParseTreeWalker.java:36)
at org.antlr.v4.runtime.tree.ParseTreeWalker.walk(ParseTreeWalker.java:36)
at org.antlr.v4.runtime.tree.ParseTreeWalker.walk(ParseTreeWalker.java:36)
at org.antlr.v4.runtime.tree.ParseTreeWalker.walk(ParseTreeWalker.java:36)
at io.debezium.antlr.AntlrDdlParser.parse(AntlrDdlParser.java:81)
at io.debezium.connector.oracle.antlr.OracleDdlParser.parse(OracleDdlParser.java:69)
at io.debezium.connector.oracle.OracleSchemaChangeEventEmitter.emitSchemaChangeEvent(OracleSchemaChangeEventEmitter.java:104)
at io.debezium.pipeline.EventDispatcher.dispatchSchemaChangeEvent(EventDispatcher.java:400)
at io.debezium.connector.oracle.logminer.processor.AbstractLogMinerEventProcessor.handleSchemaChange(AbstractLogMinerEventProcessor.java:1063)
at io.debezium.connector.oracle.logminer.processor.AbstractLogMinerEventProcessor.processRow(AbstractLogMinerEventProcessor.java:544)
at io.debezium.connector.oracle.logminer.processor.AbstractLogMinerEventProcessor.processResults(AbstractLogMinerEventProcessor.java:469)
at io.debezium.connector.oracle.logminer.processor.AbstractLogMinerEventProcessor.process(AbstractLogMinerEventProcessor.java:318)
at io.debezium.connector.oracle.logminer.LogMinerStreamingChangeEventSource.execute(LogMinerStreamingChangeEventSource.java:243)
{noformat}

The ALTER TABLE statement is:
{noformat}
alter table opr_additional_amount add part_key as (to_date(substr(lpad(to_char(oper_id), 16, '0'), 1, 6), 'yymmdd'));
{noformat}