Revert undo AbstractConvertFunction -> EsqlScalarFunction

This reverts (parts of) commit af7a60b.

Author: limotova

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/planner/EsPhysicalOperationProviders.java

@@ -66,7 +66,7 @@
 import org.elasticsearch.xpack.esql.core.type.KeywordEsField;
 import org.elasticsearch.xpack.esql.core.type.MultiTypeEsField;
 import org.elasticsearch.xpack.esql.core.type.PotentiallyUnmappedKeywordEsField;
-import org.elasticsearch.xpack.esql.expression.function.scalar.convert.AbstractConvertFunction;
+import org.elasticsearch.xpack.esql.expression.function.scalar.EsqlScalarFunction;
 import org.elasticsearch.xpack.esql.plan.physical.AggregateExec;
 import org.elasticsearch.xpack.esql.plan.physical.EsQueryExec;
 import org.elasticsearch.xpack.esql.plan.physical.EsQueryExec.Sort;
@@ -202,7 +202,7 @@ private BlockLoader getBlockLoaderFor(int shardId, Attribute attr, MappedFieldTy
             Expression conversion = unionTypes.getConversionExpressionForIndex(indexName);
             return conversion == null
                 ? BlockLoader.CONSTANT_NULLS
-                : new TypeConvertingBlockLoader(blockLoader, (AbstractConvertFunction) conversion);
+                : new TypeConvertingBlockLoader(blockLoader, (EsqlScalarFunction) conversion);
         }
         return blockLoader;
     }
@@ -542,9 +542,9 @@ private static class TypeConvertingBlockLoader implements BlockLoader {
         private final BlockLoader delegate;
         private final TypeConverter typeConverter;
 
-        protected TypeConvertingBlockLoader(BlockLoader delegate, AbstractConvertFunction convertFunction) {
+        protected TypeConvertingBlockLoader(BlockLoader delegate, EsqlScalarFunction convertFunction) {
             this.delegate = delegate;
-            this.typeConverter = TypeConverter.fromConvertFunction(convertFunction);
+            this.typeConverter = TypeConverter.fromScalarFunction(convertFunction);
         }
 
         @Override

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/planner/TypeConverter.java

@@ -17,7 +17,7 @@
 import org.elasticsearch.xpack.esql.core.expression.Expression;
 import org.elasticsearch.xpack.esql.core.expression.FoldContext;
 import org.elasticsearch.xpack.esql.evaluator.mapper.EvaluatorMapper;
-import org.elasticsearch.xpack.esql.expression.function.scalar.convert.AbstractConvertFunction;
+import org.elasticsearch.xpack.esql.expression.function.scalar.EsqlScalarFunction;
 
 class TypeConverter {
     private final String evaluatorName;
@@ -28,7 +28,7 @@ private TypeConverter(String evaluatorName, ExpressionEvaluator convertEvaluator
         this.convertEvaluator = convertEvaluator;
     }
 
-    public static TypeConverter fromConvertFunction(AbstractConvertFunction convertFunction) {
+    public static TypeConverter fromScalarFunction(EsqlScalarFunction convertFunction) {
         DriverContext driverContext1 = new DriverContext(
             BigArrays.NON_RECYCLING_INSTANCE,
             new org.elasticsearch.compute.data.BlockFactory(

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/planner/TestPhysicalOperationProviders.java

@@ -332,7 +332,7 @@ private Block getBlockForMultiType(DocBlock indexDoc, MultiTypeEsField multiType
         }
         return switch (extractBlockForSingleDoc(indexDoc, ((FieldAttribute) conversion.field()).fieldName().string(), blockCopier)) {
             case BlockResultMissing unused -> getNullsBlock(indexDoc);
-            case BlockResultSuccess success -> TypeConverter.fromConvertFunction(conversion).convert(success.block);
+            case BlockResultSuccess success -> TypeConverter.fromScalarFunction(conversion).convert(success.block);
         };
     }