Improve #docker.Push definition :

- Push to private registry
- Output ref and digest
- Update doc
- Add tests to universe.bats

Signed-off-by: Tom Chauveau <tom.chauveau@epitech.eu>

stdlib/.dagger/env/docker-push/plan/push.cue

@@ -0,0 +1,63 @@
+package docker
+
+import (
+	"dagger.io/dagger/op"
+	"dagger.io/dagger"
+	"dagger.io/docker"
+	"dagger.io/alpine"
+	"dagger.io/random"
+)
+
+TestRegistry: {
+	username: string         @dagger(input)
+	secret:   dagger.#Secret @dagger(input)
+}
+
+#TestGetSecret: {
+	secret: dagger.#Artifact
+
+	out: {
+		string
+
+		#up: [
+			op.#Load & {from: alpine.#Image},
+
+			op.#Exec & {
+				always: true
+				args: ["sh", "-c", "cp /input/secret /secret"]
+				mount: "/input/secret": "secret": secret
+			},
+
+			op.#Export & {
+				source: "/secret"
+			},
+		]
+	}
+}
+
+TestPush: {
+	tag: random.#String & {seed: "docker push and pull"}
+
+	name: "daggerio/ci-test:\(tag.out)"
+
+	secret: #TestGetSecret & {
+		secret: TestRegistry.secret
+	}
+
+	image: docker.#ImageFromDockerfile & {
+		dockerfile: """
+				FROM alpine
+				RUN echo "test" > /test.txt
+			"""
+		context: ""
+	}
+
+	push: docker.#Push & {
+		"name": name
+		source: image
+		registry: {
+			username: TestRegistry.username
+			"secret": secret.out
+		}
+	}
+}