[SPARK-56912][SQL] Refactor Cast to boolean codegen under ANSI mode

### What changes were proposed in this pull request?

Extend `CastUtils.java` with `stringToBooleanExact(UTF8String, QueryContext)`
and use it from `Cast.scala` for the ANSI `String -> Boolean` cast path
(both eval and codegen). The non-ANSI path keeps the inline
`if/else if/else evNull = true` form because it has no error to throw.

### Why are the changes needed?

Part of SPARK-56908 (umbrella). The ANSI String->Boolean cast emits an
8-line `if (isTrueString) … else if (isFalseString) … else throw` block
in codegen. This PR collapses it to a one-line `CastUtils
.stringToBooleanExact(...)` call.

### Does this PR introduce _any_ user-facing change?

No. The compiled behavior is identical; only the emitted Java source
text changes.

### How was this patch tested?

```
build/sbt "catalyst/testOnly *CastSuite *CastWithAnsiOnSuite \
  *AnsiCastSuite *TryCastSuite"
```

204/204 pass.

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: Cursor 1.x

Author: gengliangwang

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/CastUtils.java

@@ -18,10 +18,12 @@
 package org.apache.spark.sql.catalyst.expressions;
 
 import org.apache.spark.QueryContext;
+import org.apache.spark.sql.catalyst.util.StringUtils;
 import org.apache.spark.sql.errors.QueryExecutionErrors;
 import org.apache.spark.sql.types.DataType;
 import org.apache.spark.sql.types.DataTypes;
 import org.apache.spark.sql.types.Decimal;
+import org.apache.spark.unsafe.types.UTF8String;
 
 /**
  * Static helpers invoked from {@code Cast.doGenCode} so the generated Java
@@ -137,4 +139,12 @@ public static Decimal changePrecisionExact(
   public static Decimal changePrecisionOrNull(Decimal d, int precision, int scale) {
     return d.changePrecision(precision, scale) ? d : null;
   }
+
+  // ----- string -> boolean (ANSI: throw on invalid syntax) -----
+
+  public static boolean stringToBooleanExact(UTF8String s, QueryContext context) {
+    if (StringUtils.isTrueString(s)) return true;
+    if (StringUtils.isFalseString(s)) return false;
+    throw QueryExecutionErrors.invalidInputSyntaxForBooleanError(s, context);
+  }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala

@@ -695,18 +695,16 @@ case class Cast(
 
   // UDFToBoolean
   private[this] def castToBoolean(from: DataType): Any => Any = from match {
+    case _: StringType if ansiEnabled =>
+      buildCast[UTF8String](_, s => CastUtils.stringToBooleanExact(s, getContextOrNull()))
     case _: StringType =>
       buildCast[UTF8String](_, s => {
         if (StringUtils.isTrueString(s)) {
           true
         } else if (StringUtils.isFalseString(s)) {
           false
         } else {
-          if (ansiEnabled) {
-            throw QueryExecutionErrors.invalidInputSyntaxForBooleanError(s, getContextOrNull())
-          } else {
-            null
-          }
+          null
         }
       })
     case TimestampType =>
@@ -1891,22 +1889,20 @@ case class Cast(
   private[this] def castToBooleanCode(
       from: DataType,
       ctx: CodegenContext): CastFunction = from match {
+    case _: StringType if ansiEnabled =>
+      val castUtils = classOf[CastUtils].getName
+      val errorContext = getContextOrNullCode(ctx)
+      (c, evPrim, _) => code"$evPrim = $castUtils.stringToBooleanExact($c, $errorContext);"
     case _: StringType =>
       val stringUtils = inline"${StringUtils.getClass.getName.stripSuffix("$")}"
       (c, evPrim, evNull) =>
-        val castFailureCode = if (ansiEnabled) {
-          val errorContext = getContextOrNullCode(ctx)
-          s"throw QueryExecutionErrors.invalidInputSyntaxForBooleanError($c, $errorContext);"
-        } else {
-          s"$evNull = true;"
-        }
         code"""
           if ($stringUtils.isTrueString($c)) {
             $evPrim = true;
           } else if ($stringUtils.isFalseString($c)) {
             $evPrim = false;
           } else {
-            $castFailureCode
+            $evNull = true;
           }
         """
     case TimestampType =>