feat(refacto): move everything in internal package

This allows to install katenary with `go install` and to clean up the
project folder.

internal/generator/labels/labelstructs/ports_test.go

@@ -0,0 +1,23 @@
+package labelstructs
+
+import "testing"
+
+func TestPortsFromLabel(t *testing.T) {
+	data := "- 8080\n- 9090\n"
+	expected := Ports{8080, 9090}
+
+	ports, err := PortsFrom(data)
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+
+	if len(ports) != len(expected) {
+		t.Fatalf("expected length %d, got %d", len(expected), len(ports))
+	}
+
+	for i, port := range ports {
+		if port != expected[i] {
+			t.Errorf("expected port %d at index %d, got %d", expected[i], i, port)
+		}
+	}
+}