checker: relax the redundant () check to a notice, to enable a future v -W test vlib/builtin job on the CI

Author: spytheman

vlib/v/checker/checker.v

@@ -3353,7 +3353,7 @@ pub fn (mut c Checker) expr(mut node ast.Expr) ast.Type {
 		// }
 		ast.ParExpr {
 			if node.expr is ast.ParExpr {
-				c.warn('redundant parentheses are used', node.pos)
+				c.note('redundant parentheses are used', node.pos)
 			}
 			return c.expr(mut node.expr)
 		}

vlib/v/checker/tests/assign_immutable_reference_var_with_parenthesis_err.out

@@ -1,11 +1,11 @@
-vlib/v/checker/tests/assign_immutable_reference_var_with_parenthesis_err.vv:11:12: warning: redundant parentheses are used
+vlib/v/checker/tests/assign_immutable_reference_var_with_parenthesis_err.vv:11:12: notice: redundant parentheses are used
     9 | fn foo() {
    10 |     mut a := &(a_char)
    11 |     mut b := &((a_char))
       |               ~~~~~~~~~~
    12 |     mut c := &((((a_char))))
    13 |     println(a)
-vlib/v/checker/tests/assign_immutable_reference_var_with_parenthesis_err.vv:12:12: warning: redundant parentheses are used
+vlib/v/checker/tests/assign_immutable_reference_var_with_parenthesis_err.vv:12:12: notice: redundant parentheses are used
    10 |     mut a := &(a_char)
    11 |     mut b := &((a_char))
    12 |     mut c := &((((a_char))))

vlib/v/checker/tests/par_expr_assign_void_right_type_err.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/par_expr_assign_void_right_type_err.vv:1:6: warning: redundant parentheses are used
+vlib/v/checker/tests/par_expr_assign_void_right_type_err.vv:1:6: notice: redundant parentheses are used
     1 | _ := ((((print(10)))))
       |      ~~~~~~~~~~~~~~~~~
 vlib/v/checker/tests/par_expr_assign_void_right_type_err.vv:1:3: error: assignment mismatch: expected 1 value(s) but `print()` returns 0 value(s)

vlib/v/checker/tests/redundant_parentheses_warning.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/redundant_parentheses_warning.vv:3:7: warning: redundant parentheses are used
+vlib/v/checker/tests/redundant_parentheses_warning.vv:3:7: notice: redundant parentheses are used
     1 | fn main() {
     2 |     a := 2
     3 |     b := ((a + 2))