[FIR/IR generator] Rename field's needAcceptAndTransform to isChild

This better describes the semantics.

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/AbstractField.kt

@@ -57,11 +57,14 @@ abstract class AbstractField<Field : AbstractField<Field>> {
     var useInBaseTransformerDetection = true
 
     /**
-     * Whether a visitor should be run on this field in the generated `acceptChildren` in `transformChildren` method.
+     * Whether this field semantically represents a reference to a child node of the tree.
+     *
+     * This may have the effect of including or excluding this field from visiting it by visitors in the generated
+     * `acceptChildren` and `transformChildren` methods (child fields are always visited in those methods).
      *
      * Only has effect if [containsElement] is `true`.
      */
-    var needAcceptAndTransform: Boolean = true
+    var isChild: Boolean = true
 
     open val overriddenTypes: MutableSet<TypeRefWithNullability> = mutableSetOf()
 
@@ -103,7 +106,7 @@ abstract class AbstractField<Field : AbstractField<Field>> {
         copy.visibility = visibility
         copy.fromParent = fromParent
         copy.useInBaseTransformerDetection = useInBaseTransformerDetection
-        copy.needAcceptAndTransform = needAcceptAndTransform
+        copy.isChild = isChild
         copy.overriddenTypes += overriddenTypes
     }
 }

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/FieldContainer.kt

@@ -37,7 +37,7 @@ interface FieldContainer<out Field : AbstractField<*>> {
      */
     val walkableChildren: List<Field>
         get() = allFields
-            .filter { it.containsElement && !it.withGetter && it.needAcceptAndTransform }
+            .filter { it.containsElement && !it.withGetter && it.isChild }
             .reorderFieldsIfNecessary(childrenOrderOverride)
 
     /**

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/config/AbstractImplementationConfigurator.kt

@@ -378,16 +378,18 @@ abstract class AbstractImplementationConfigurator<Implementation, Element, Imple
                 }
 
             /**
-             * Allows to exclude this field from visiting it by visitors in the generated `acceptChildren` and `transformChildren`
-             * methods.
+             * Whether this field semantically represents a reference to a child node of the tree.
+             *
+             * This has the effect of including or excluding this field from visiting it by visitors in the generated
+             * `acceptChildren` and `transformChildren` methods (child fields are always visited in those methods)
              */
-            var needAcceptAndTransform: Boolean = true
+            var isChild: Boolean = true
 
             fun applyConfiguration() {
                 field.withGetter = withGetter
                 field.customSetter = customSetter
                 isMutable?.let { field.isMutable = it }
-                field.needAcceptAndTransform = needAcceptAndTransform
+                field.isChild = isChild
 
                 when {
                     value != null -> field.defaultValueInImplementation = value