[SPARK-36312][SQL][FOLLOWUP] Add back ParquetSchemaConverter.checkFie…

…ldNames

### What changes were proposed in this pull request?
Add back ParquetSchemaConverter.checkFieldNames()

### Why are the changes needed?
Fix code

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?

Closes #33552 from AngersZhuuuu/SPARK-36312-FOLLOWUP.

Authored-by: Angerszhuuuu <angers.zhu@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetSchemaConverter.scala

@@ -591,6 +591,16 @@ private[sql] object ParquetSchemaConverter {
     }
   }
 
+  def checkFieldNames(schema: StructType): Unit = {
+    schema.foreach { field =>
+      checkFieldName(field.name)
+      field.dataType match {
+        case s: StructType => checkFieldNames(s)
+        case _ =>
+      }
+    }
+  }
+
   def checkConversionRequirement(f: => Boolean, message: String): Unit = {
     if (!f) {
       throw new AnalysisException(message)