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/docker/tests/load/load.cue

@@ -0,0 +1,32 @@
+package docker
+
+import (
+	"alpha.dagger.io/dagger"
+	"alpha.dagger.io/random"
+)
+
+dockersocket: dagger.#Stream & dagger.#Input
+
+source: dagger.#Artifact & dagger.#Input
+
+TestLoad: {
+	suffix: random.#String & {
+		seed: ""
+	}
+
+	image: #Build & {
+		"source": source
+	}
+
+	load: #Load & {
+		tag:    "daggerci-image-load-\(suffix.out)"
+		source: image
+		socket: dockersocket
+	}
+
+	run: #Run & {
+		name:   "daggerci-container-load-\(suffix.out)"
+		ref:    load.id
+		socket: dockersocket
+	}
+}