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/build/dockerfile.cue

@@ -0,0 +1,84 @@
+package docker
+
+import (
+	"alpha.dagger.io/dagger"
+	"alpha.dagger.io/dagger/op"
+)
+
+TestSourceBuild: dagger.#Artifact @dagger(input)
+
+TestBuild: {
+	image: #Build & {
+		source: TestSourceBuild
+	}
+
+	verify: #up: [
+		op.#Load & {
+			from: image
+		},
+
+		op.#Exec & {
+			always: true
+			args: [
+				"sh", "-c", """
+						grep -q "test" /test.txt
+					""",
+			]
+		},
+	]
+}
+
+TestBuildWithArgs: {
+	image: #Build & {
+		dockerfile: """
+				FROM alpine
+				ARG TEST
+				ENV TEST=$TEST
+				RUN echo "$TEST" > /test.txt
+			"""
+		source: ""
+		args: TEST: "test"
+	}
+
+	verify: #up: [
+		op.#Load & {
+			from: image
+		},
+
+		op.#Exec & {
+			always: true
+			args: [
+				"sh", "-c", """
+						grep -q "test" /test.txt
+					""",
+			]
+		},
+	]
+}
+
+TestSourceImageFromDockerfile: dagger.#Artifact @dagger(input)
+
+TestImageFromDockerfile: {
+	image: #Build & {
+		dockerfile: """
+				FROM alpine
+				COPY test.txt /test.txt
+			"""
+		source: TestSourceImageFromDockerfile
+	}
+
+	verify: #up: [
+		op.#Load & {
+			from: image
+		},
+
+		op.#Exec & {
+			always: true
+			args: [
+				"sh", "-c", """
+						grep -q "test" /test.txt
+					""",
+			]
+		},
+	]
+}

pkg/alpha.dagger.io/docker/tests/build/testdata/build/Dockerfile

@@ -0,0 +1,2 @@
+FROM alpine
+RUN echo test >> /test.txt

pkg/alpha.dagger.io/docker/tests/build/testdata/dockerfile/test.txt

@@ -0,0 +1 @@
+test