cue modules: move stdlib to pkg/alpha.dagger.io

In preparation for Europa, we will vendor multiple CUE modules:

- `pkg/alpha.dagger.io`: legacy non-europa packages
- `pkg/dagger.io`: core Europa packages
- `pkg/universe.dagger.io`: Europa universe

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

pkg/alpha.dagger.io/aws/ecr/ecr.cue

@@ -0,0 +1,32 @@
+// Amazon Elastic Container Registry (ECR)
+package ecr
+
+import (
+	"alpha.dagger.io/aws"
+	"alpha.dagger.io/os"
+)
+
+// Convert ECR credentials to Docker Login format
+#Credentials: {
+	// AWS Config
+	config: aws.#Config
+
+	// ECR registry
+	username: "AWS" @dagger(output)
+
+	ctr: os.#Container & {
+		image: aws.#CLI & {
+			"config": config
+		}
+		always:  true
+		command: "aws ecr get-login-password > /out"
+	}
+
+	// ECR registry secret
+	secret: {
+		os.#File & {
+				from: ctr
+				path: "/out"
+			}
+	}.contents @dagger(output)
+}