[Spark] Support 3-part naming in table identifier parsing

-Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [ ] Other (fill in here)

Support 3-part naming in table identifier parsing. Before the changes, the following command
```
OPTIMIZE catalog_foo.db.tbl
```
will throw error
```
org.apache.spark.sql.delta.DeltaParseException:
Illegal table name catalog_foo.db.tbl(line 1, pos 9)

== SQL ==
optimize catalog_foo.db.tbl
---------^^^

  at io.delta.sql.parser.DeltaSqlAstBuilder.$anonfun$visitTableIdentifier$1(DeltaSqlParser.scala:430)
  at org.apache.spark.sql.catalyst.parser.ParserUtils$.withOrigin(ParserUtils.scala:160)
  at io.delta.sql.parser.DeltaSqlAstBuilder.visitTableIdentifier(DeltaSqlParser.scala:427)
  at io.delta.sql.parser.DeltaSqlAstBuilder.$anonfun$visitOptimizeTable$5(DeltaSqlParser.scala:348)
  at scala.Option.map(Option.scala:230)
  at io.delta.sql.parser.DeltaSqlAstBuilder.$anonfun$visitOptimizeTable$1(DeltaSqlParser.scala:348)
```
After the changes, the command works.

A new unit test

No

Closes #1985

Signed-off-by: Venki Korukanti <venki.korukanti@databricks.com>
GitOrigin-RevId: dd297a9d8e77a6fdfafb834c74a915de1aeae737

spark/src/main/scala/io/delta/sql/parser/DeltaSqlParser.scala

@@ -427,6 +427,8 @@ class DeltaSqlAstBuilder extends DeltaSqlBaseBaseVisitor[AnyRef] {
     ctx.identifier.asScala.toSeq match {
       case Seq(tbl) => TableIdentifier(tbl.getText)
       case Seq(db, tbl) => TableIdentifier(tbl.getText, Some(db.getText))
+      case Seq(catalog, db, tbl) =>
+        TableIdentifier(tbl.getText, Some(db.getText), Some(catalog.getText))
       case _ => throw new DeltaParseException(s"Illegal table name ${ctx.getText}", ctx)
     }
   }

spark/src/test/scala/io/delta/sql/parser/DeltaSqlParserSuite.scala

@@ -62,6 +62,12 @@ class DeltaSqlParserSuite extends SparkFunSuite with SQLHelper {
     assert(parsedCmd.asInstanceOf[OptimizeTableCommand].child ===
       UnresolvedTable(Seq("db", "tbl"), "OPTIMIZE", None))
 
+    parsedCmd = parser.parsePlan("OPTIMIZE catalog_foo.db.tbl")
+    assert(parsedCmd ===
+      OptimizeTableCommand(None, Some(tblId("tbl", "db", "catalog_foo")), Nil)(Nil))
+    assert(parsedCmd.asInstanceOf[OptimizeTableCommand].child ===
+      UnresolvedTable(Seq("catalog_foo", "db", "tbl"), "OPTIMIZE", None))
+
     assert(parser.parsePlan("OPTIMIZE tbl_${system:spark.testing}") ===
       OptimizeTableCommand(None, Some(tblId("tbl_true")), Nil)(Nil))
 
@@ -230,7 +236,7 @@ class DeltaSqlParserSuite extends SparkFunSuite with SQLHelper {
               versionAsOf,
               Some("sql"))
           },
-          UnresolvedRelation(tblId(target)),
+          new UnresolvedRelation(target.split('.')),
           ifNotExists = false,
           isReplaceCommand = isReplace,
           isCreateCommand = isCreate,
@@ -260,11 +266,8 @@ class DeltaSqlParserSuite extends SparkFunSuite with SQLHelper {
     checkCloneStmt(parser, source = "t1", target = "t1", versionAsOf = Some(1L))
     // Clone with 3L table (only useful for Iceberg table now)
     checkCloneStmt(parser, source = "local.iceberg.table", target = "t1", sourceIs3LTable = true)
-    // Yet target cannot be a 3L table yet
-    intercept[ParseException] {
-      checkCloneStmt(parser, source = "local.iceberg.table", target = "catalog.delta.table",
-        sourceIs3LTable = true)
-    }
+    checkCloneStmt(parser, source = "local.iceberg.table", target = "delta.table",
+      sourceIs3LTable = true)
     // Custom source format with path
     checkCloneStmt(parser, source = "/path/to/iceberg", target = "t1", sourceFormat = "iceberg",
       sourceIsTable = false)
@@ -274,8 +277,16 @@ class DeltaSqlParserSuite extends SparkFunSuite with SQLHelper {
     new UnresolvedAttribute(colName)
   }
 
-  private def tblId(tblName: String, schema: String = null): TableIdentifier = {
-    if (schema == null) new TableIdentifier(tblName)
-    else new TableIdentifier(tblName, Some(schema))
+  private def tblId(
+      tblName: String,
+      schema: String = null,
+      catalog: String = null): TableIdentifier = {
+    if (catalog == null) {
+      if (schema == null) new TableIdentifier(tblName)
+      else new TableIdentifier(tblName, Some(schema))
+    } else {
+      assert(schema != null)
+      new TableIdentifier(tblName, Some(schema), Some(catalog))
+    }
   }
 }