checker, cgen: implement method map() for fixed arrays (#22644)

vlib/builtin/fixed_array_map_test.v

@@ -0,0 +1,27 @@
+fn test_fixed_array_map() {
+	a := [1, 2, 3]!
+
+	b1 := a.map(it * 2)
+	println(b1)
+	assert b1 == [2, 4, 6]!
+
+	b11 := a.map(|x| x * 2)
+	println(b11)
+	assert b11 == [2, 4, 6]!
+
+	b2 := a.map('${it}')
+	println(b2)
+	assert b2 == ['1', '2', '3']!
+
+	b22 := a.map(|x| '${x}')
+	println(b22)
+	assert b22 == ['1', '2', '3']!
+
+	b3 := a.map(it + 2)
+	println(b3)
+	assert b3 == [3, 4, 5]!
+
+	b33 := a.map(|x| x + 2)
+	println(b33)
+	assert b33 == [3, 4, 5]!
+}