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/bats/bats.cue

@@ -0,0 +1,56 @@
+package bats
+
+import (
+	"strings"
+
+	"alpha.dagger.io/dagger"
+	"alpha.dagger.io/os"
+	"alpha.dagger.io/alpine"
+)
+
+#Bats: {
+	// Source containing bats files
+	source: dagger.#Artifact & dagger.#Input
+
+	// bats options
+	options: [...string]
+
+	// mount points passed to the bats container
+	mount: [string]: from: dagger.#Artifact
+
+	// environment variables
+	env: [string]: string
+
+	// socket mounts for the bats container
+	socket: [string]: dagger.#Stream
+
+	// setup commands to run only once (for installing dependencies)
+	setupCommands: [...string]
+
+	// init script to run right before bats
+	initScript: string | *""
+
+	defaultOptions: ["--print-output-on-failure", "--show-output-of-passing-tests"]
+
+	ctr: os.#Container & {
+		image: alpine.#Image & {
+			package: curl: true
+			package: bash: true
+			package: jq:   true
+			package: npm:  true
+			package: git:  true
+		}
+		shell: path: "/bin/bash"
+		setup:   ["npm install -g bats"] + setupCommands
+		command: #"""
+            \#(initScript)
+            bats \#(strings.Join(defaultOptions, " ")) \#(strings.Join(options, " ")) ../src
+            """#
+
+		dir:     "/app"
+		"mount": mount
+		"mount": "/src": from: source
+		"env":    env
+		"socket": socket
+	}
+}