Handle SIGN function properly in HQL and JPQL queries.

See #2994.

spring-data-jpa/src/main/antlr4/org/springframework/data/jpa/repository/query/Hql.g4

@@ -1013,7 +1013,6 @@ SEARCH                      : S E A R C H;
 SECOND                      : S E C O N D;
 SELECT                      : S E L E C T;
 SET                         : S E T;
-SIGN                        : S I G N;
 SIZE                        : S I Z E;
 SOME                        : S O M E;
 SUBSTRING                   : S U B S T R I N G;

spring-data-jpa/src/main/antlr4/org/springframework/data/jpa/repository/query/Jpql.g4

@@ -602,7 +602,8 @@ identification_variable
     | LEFT
     | ORDER
     | OUTER
-    | FLOOR)
+    | FLOOR
+    | SIGN)
     ;
 
 constructor_name

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/HqlQueryRendererTests.java

@@ -1516,4 +1516,9 @@ class HqlQueryRendererTests {
 				WHERE f.name = :name
 				""");
 	}
+
+	@Test // GH-2994
+	void queryWithSignShouldWork() {
+		assertQuery("select t.sign from TestEntity t");
+	}
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/JpqlQueryRendererTests.java

@@ -931,4 +931,9 @@ class JpqlQueryRendererTests {
 				WHERE f.name = :name
 				""");
 	}
+
+	@Test // GH-2994
+	void queryWithSignShouldWork() {
+		assertQuery("select t.sign from TestEntity t");
+	}
 }