CloudMigrations: wire ngalert to cloud migration service and add slicesext.Map helper (#94254)

* CloudMigrations: add slicesext.Map function to simplify dto creation

* CloudMigrations: wire ngalert to cloud migration service

pkg/services/cloudmigration/slicesext/slicesext.go

@@ -0,0 +1,11 @@
+package slicesext
+
+func Map[T any, U any](xs []T, f func(T) U) []U {
+	out := make([]U, 0, len(xs))
+
+	for _, x := range xs {
+		out = append(out, f(x))
+	}
+
+	return out
+}

pkg/services/cloudmigration/slicesext/slicesext_test.go

@@ -0,0 +1,36 @@
+package slicesext_test
+
+import (
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/grafana/grafana/pkg/services/cloudmigration/slicesext"
+)
+
+func TestMap(t *testing.T) {
+	t.Parallel()
+
+	t.Run("mapping a nil slice does nothing and returns an empty slice", func(t *testing.T) {
+		t.Parallel()
+
+		require.Empty(t, slicesext.Map[any, any](nil, nil))
+	})
+
+	t.Run("mapping a non-nil slice with a nil function panics", func(t *testing.T) {
+		t.Parallel()
+
+		require.Panics(t, func() { slicesext.Map[int, any]([]int{1, 2, 3}, nil) })
+	})
+
+	t.Run("mapping a non-nil slice with a non-nil function returns the mapped slice", func(t *testing.T) {
+		t.Parallel()
+
+		original := []int{1, 2, 3}
+		expected := []string{"1", "2", "3"}
+		fn := func(i int) string { return strconv.Itoa(i) }
+
+		require.ElementsMatch(t, expected, slicesext.Map(original, fn))
+	})
+}