[SPARK-48709][SQL][3.5] Fix varchar type resolution mismatch for DataSourceV2 CTAS

Backport of #47082.

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

This PR fixes varchar type resolution mismatch for DataSourceV2 CTAS. For example:
```sql
set spark.sql.storeAssignmentPolicy=LEGACY;
CREATE TABLE testcat.ns.t1 (d1 string, d2 varchar(200)) USING parquet;
CREATE TABLE testcat.ns.t2 USING foo as select * from testcat.ns.t1
```
Error message:
```
org.apache.spark.sql.AnalysisException: LEGACY store assignment policy is disallowed in Spark data source V2. Please set the configuration spark.sql.storeAssignmentPolicy to other values.
```

### Why are the changes needed?

Avoid query failures.

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

No.

### How was this patch tested?

Unit test.

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

No.

Closes #47103 from wangyum/SPARK-48709-branch-3.5.

Authored-by: Yuming Wang <[email protected]>
Signed-off-by: Kent Yao <[email protected]>

Author: wangyum

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/v2Commands.scala

@@ -62,10 +62,11 @@ trait V2WriteCommand extends UnaryCommand with KeepAnalyzedQuery {
     table.skipSchemaResolution || (query.output.size == table.output.size &&
       query.output.zip(table.output).forall {
         case (inAttr, outAttr) =>
+          val inType = CharVarcharUtils.getRawType(inAttr.metadata).getOrElse(inAttr.dataType)
           val outType = CharVarcharUtils.getRawType(outAttr.metadata).getOrElse(outAttr.dataType)
           // names and types must match, nullability must be compatible
           inAttr.name == outAttr.name &&
-            DataType.equalsIgnoreCompatibleNullability(inAttr.dataType, outType) &&
+            DataType.equalsIgnoreCompatibleNullability(inType, outType) &&
             (outAttr.nullable || !inAttr.nullable)
       })
   }

sql/core/src/test/scala/org/apache/spark/sql/connector/DataSourceV2SQLSuite.scala

@@ -1736,6 +1736,16 @@ class DataSourceV2SQLSuiteV1Filter
     }
   }
 
+  test("SPARK-48709: varchar resolution mismatch for DataSourceV2 CTAS") {
+    withSQLConf(
+      SQLConf.STORE_ASSIGNMENT_POLICY.key -> SQLConf.StoreAssignmentPolicy.LEGACY.toString) {
+      withTable("testcat.ns.t1", "testcat.ns.t2") {
+        sql("CREATE TABLE testcat.ns.t1 (d1 string, d2 varchar(200)) USING parquet")
+        sql("CREATE TABLE testcat.ns.t2 USING foo as select * from testcat.ns.t1")
+      }
+    }
+  }
+
   test("ShowCurrentNamespace: basic tests") {
     def testShowCurrentNamespace(expectedCatalogName: String, expectedNamespace: String): Unit = {
       val schema = new StructType()