feat: DH-21522: allow column region optimizations in Predicate Pushdown filtering (#7666)

This PR refactors predicate pushdown filtering for regioned column
sources to support both table-location and per-column-region
optimizations, enabling more granular (region-level) pushdown planning
and execution.

**Changes:**
- Introduces a new `RegionedPushdownAction` model (Location vs Region
actions) and new regioned pushdown filter context types.
- Updates regioned pushdown execution to run per-region and merge
results, enabling column-region pushdown participation.
- Refactors `ParquetTableLocation` pushdown logic from an internal enum
to the new action-based API and updates the engine interfaces
accordingly.


Code Coverage Summary:
- ImmutableConstant[Type]Source
  - makePushdownFilterContext / estimatePushdownFilterCost at 100%
- pushdownFilter effectively 100% (empty selection detection not tested,
might not be reachable without dedicated test)

Author: lbooker42

engine/chunk/src/main/java/io/deephaven/chunk/WritableBooleanChunk.java

@@ -10,7 +10,9 @@
 import io.deephaven.chunk.attributes.Any;
 import io.deephaven.chunk.util.pools.MultiChunkPool;
 
+import io.deephaven.function.ArraySort;
 import io.deephaven.util.type.TypeUtils;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.Arrays;
 // region FillWithNullValueImports

engine/chunk/src/main/java/io/deephaven/chunk/WritableObjectChunk.java

@@ -11,6 +11,8 @@
 import io.deephaven.chunk.util.pools.MultiChunkPool;
 
 import io.deephaven.function.ArraySort;
+import io.deephaven.util.type.TypeUtils;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.Arrays;
 // region FillWithNullValueImports

engine/table/src/main/java/io/deephaven/engine/table/impl/AbstractColumnSource.java

@@ -164,7 +164,7 @@ public void estimatePushdownFilterCost(
             final LongConsumer onComplete,
             final Consumer<Exception> onError) {
         // Default to having no benefit by pushing down.
-        onComplete.accept(Long.MAX_VALUE);
+        onComplete.accept(PushdownResult.UNSUPPORTED_ACTION_COST);
     }
 
     @Override

engine/table/src/main/java/io/deephaven/engine/table/impl/AbstractFilterExecution.java

@@ -36,6 +36,8 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import static io.deephaven.engine.table.impl.PushdownResult.UNSUPPORTED_ACTION_COST;
+
 /**
  * The AbstractFilterExecution incorporates the idea that we have an added and modified RowSet to filter and that there
  * are a resulting pair of added and modified rows representing what was filtered. There is also the possibility that we
@@ -210,7 +212,7 @@ private class StatelessFilter implements Comparable<StatelessFilter>, SafeClosea
         /**
          * The cost of the pushdown filter operation.
          */
-        public long pushdownFilterCost = Long.MAX_VALUE;
+        public long pushdownFilterCost = UNSUPPORTED_ACTION_COST;
         /**
          * The result of the pushdown filter operation, or null if pushdown is not supported.
          */
@@ -250,12 +252,13 @@ public StatelessFilter(
 
         /**
          * Schedules pushdown filter cost estimation for {@link #pushdownMatcher}. After {@link #pushdownFilterCost} has
-         * been set (or set to {@link Long#MAX_VALUE} if pushdown is not supported), {@code onComplete} will be called.
+         * been set (or set to {@link PushdownResult#UNSUPPORTED_ACTION_COST} if pushdown is not supported),
+         * {@code onComplete} will be called.
          */
         public void scheduleUpdatePushdownFilterCost(final RowSet selection, final Runnable onComplete,
                 final Consumer<Exception> onError) {
             if (pushdownMatcher == null) {
-                pushdownFilterCost = Long.MAX_VALUE;
+                pushdownFilterCost = UNSUPPORTED_ACTION_COST;
                 onComplete.run();
                 return;
             }
@@ -443,7 +446,7 @@ private void executeStatelessFilter(
         };
 
         final RowSet input = localInput.get();
-        if (sf.pushdownMatcher != null && sf.pushdownFilterCost < Long.MAX_VALUE) {
+        if (sf.pushdownMatcher != null && sf.pushdownFilterCost != UNSUPPORTED_ACTION_COST) {
             // Execute the pushdown filter and return.
             sf.pushdownMatcher.pushdownFilter(sf.filter, input, usePrev, sf.context,
                     costCeiling, jobScheduler(), onPushdownComplete, filterNec);