checker, cgen: implement methods reverse()/reverse_in_place() for fixed arrays (#22712)

vlib/builtin/fixed_array_reverse_test.v

@@ -0,0 +1,52 @@
+struct User {
+	age  int
+	name string
+}
+
+fn test_fixed_array_reverse_in_place() {
+	mut a := ['hi', '1', '5', '3']!
+	a.reverse_in_place()
+	assert a == ['3', '5', '1', 'hi']!
+
+	mut nums := [67, -3, 108, 42, 7]!
+	nums.reverse_in_place()
+	assert nums == [7, 42, 108, -3, 67]!
+
+	mut users := [User{22, 'Peter'}, User{20, 'Bob'}, User{25, 'Alice'}]!
+	users.reverse_in_place()
+	assert users[0].age == 25
+	assert users[1].age == 20
+	assert users[2].age == 22
+	assert users[0].name == 'Alice'
+	assert users[1].name == 'Bob'
+	assert users[2].name == 'Peter'
+}
+
+fn test_fixed_array_reverse() {
+	a := ['hi', '1', '5', '3']!
+	b := a.reverse()
+	assert a == ['hi', '1', '5', '3']!
+	assert b == ['3', '5', '1', 'hi']!
+
+	mut nums := [67, -3, 108, 42, 7]!
+	n := nums.reverse()
+	assert nums == [67, -3, 108, 42, 7]!
+	assert n == [7, 42, 108, -3, 67]!
+
+	mut users := [User{22, 'Peter'}, User{20, 'Bob'}, User{25, 'Alice'}]!
+	u := users.reverse()
+
+	assert users[0].age == 22
+	assert users[1].age == 20
+	assert users[2].age == 25
+	assert users[0].name == 'Peter'
+	assert users[1].name == 'Bob'
+	assert users[2].name == 'Alice'
+
+	assert u[0].age == 25
+	assert u[1].age == 20
+	assert u[2].age == 22
+	assert u[0].name == 'Alice'
+	assert u[1].name == 'Bob'
+	assert u[2].name == 'Peter'
+}