[SPARK-3708][SQL] Backticks aren't handled correctly is aliases

The below query gives error
sql("SELECT k FROM (SELECT \`key\` AS \`k\` FROM src) a")
It gives error because the aliases are not cleaned so it could not be resolved in further processing.

Author: ravipesala <[email protected]>

Closes #2594 from ravipesala/SPARK-3708 and squashes the following commits:

d55db54 [ravipesala] Fixed SPARK-3708 (Backticks aren't handled correctly is aliases)

Author: ravipesala

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala

@@ -855,7 +855,7 @@ private[hive] object HiveQl {
 
     case Token("TOK_SELEXPR",
            e :: Token(alias, Nil) :: Nil) =>
-      Some(Alias(nodeToExpr(e), alias)())
+      Some(Alias(nodeToExpr(e), cleanIdentifier(alias))())
 
     /* Hints are ignored */
     case Token("TOK_HINTLIST", _) => None

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala

@@ -63,4 +63,10 @@ class SQLQuerySuite extends QueryTest {
       sql("SELECT key, value FROM test_ctas_123 ORDER BY key"), 
       sql("SELECT key, value FROM src ORDER BY key").collect().toSeq)
   }
+
+  test("SPARK-3708 Backticks aren't handled correctly is aliases") {
+    checkAnswer(
+      sql("SELECT k FROM (SELECT `key` AS `k` FROM src) a"),
+      sql("SELECT `key` FROM src").collect().toSeq)
+  }  
 }