Boolean expression on top of a MV column filter fails

Attempting to execute a query like `SELECT * FROM table WHERE (mvCol = 'test') = true`, fails with the exception:

```
2023/03/25 01:17:47.521 ERROR [BaseCombineOperator] [pqw-2] Caught exception while processing query: QueryContext{_tableName='random_REALTIME', _subquery=null, _selectExpressions=[multiCol, timestamp], _aliasList=[null, null], _filter=equals(multiCol,'null') = 'true', _groupByExpressions=null, _havingFilter=null, _orderByExpressions=null, _limit=10, _offset=0, _queryOptions={responseFormat=sql, groupByMode=sql, timeoutMs=9999}, _expressionOverrideHints={}, _explain=false}
java.lang.UnsupportedOperationException: null
at org.apache.pinot.segment.spi.index.mutable.MutableForwardIndex.readDictIds(MutableForwardIndex.java:74) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.segment.spi.index.mutable.MutableForwardIndex.readDictIds(MutableForwardIndex.java:79) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.common.DataFetcher$ColumnValueReader.readStringValues(DataFetcher.java:570) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.common.DataFetcher.fetchStringValues(DataFetcher.java:239) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.common.DataBlockCache.getStringValuesForSVColumn(DataBlockCache.java:277) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.docvalsets.ProjectionBlockValSet.getStringValuesSV(ProjectionBlockValSet.java:153) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.transform.function.IdentifierTransformFunction.transformToStringValuesSV(IdentifierTransformFunction.java:111) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.transform.function.BinaryOperatorTransformFunction.fillResultString(BinaryOperatorTransformFunction.java:284) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.transform.function.BinaryOperatorTransformFunction.fillResultArray(BinaryOperatorTransformFunction.java:135) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.transform.function.BinaryOperatorTransformFunction.transformToIntValuesSV(BinaryOperatorTransformFunction.java:109) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.dociditerators.ExpressionScanDocIdIterator.processProjectionBlock(ExpressionScanDocIdIterator.java:156) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.dociditerators.ExpressionScanDocIdIterator.next(ExpressionScanDocIdIterator.java:88) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.DocIdSetOperator.getNextBlock(DocIdSetOperator.java:75) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.DocIdSetOperator.getNextBlock(DocIdSetOperator.java:39) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.BaseOperator.nextBlock(BaseOperator.java:43) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.ProjectionOperator.getNextBlock(ProjectionOperator.java:70) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.ProjectionOperator.getNextBlock(ProjectionOperator.java:37) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.BaseOperator.nextBlock(BaseOperator.java:43) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.query.SelectionOnlyOperator.getNextBlock(SelectionOnlyOperator.java:97) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.query.SelectionOnlyOperator.getNextBlock(SelectionOnlyOperator.java:41) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.BaseOperator.nextBlock(BaseOperator.java:43) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.combine.BaseSingleBlockCombineOperator.processSegments(BaseSingleBlockCombineOperator.java:102) ~[pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.operator.combine.BaseCombineOperator$1.runJob(BaseCombineOperator.java:107) [pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.core.util.trace.TraceRunnable.run(TraceRunnable.java:40) [pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:264) [?:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at org.apache.pinot.shaded.com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:111) [pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.shaded.com.google.common.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:58) [pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at org.apache.pinot.shaded.com.google.common.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:75) [pinot-all-0.13.0-SNAPSHOT-jar-with-dependencies.jar:0.13.0-SNAPSHOT-3f36623c563b5ad495a502a00f627b44bfc0861d]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
at java.lang.Thread.run(Thread.java:829) [?:?]
```

# Version
apache/pinot@3f36623

Reproduce the Boolean expression query against the Pinot version identified in the report, then trace the failure from MutableForwardIndex.readDictIds through DataFetcher and BinaryOperatorTransformFunction. Compare the MV-column filter path with the expression scan path shown in the stack trace. Done means the query executes without the UnsupportedOperationException and preserves the expected filter behavior.

Written by the indexing model from the issue text.