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/.dagger/env/sanity-check/plan/cue.mod/module.cue

@@ -0,0 +1 @@
+module: ""

pkg/alpha.dagger.io/.dagger/env/sanity-check/plan/cue.mod/pkg/.gitignore

@@ -0,0 +1,3 @@
+# generated by dagger
+alpha.dagger.io
+dagger.lock

pkg/alpha.dagger.io/.dagger/env/sanity-check/plan/main.cue

@@ -0,0 +1,69 @@
+package main
+
+import (
+	"alpha.dagger.io/dagger"
+	"alpha.dagger.io/os"
+	"alpha.dagger.io/alpine"
+)
+
+// Assert that there are no errors
+err: ""
+
+// Directory containing universe packages (./universe/ in dagger repo)
+universe: dagger.#Input & dagger.#Artifact
+
+ctr: #CueCLI & {
+	ctx: universe
+	command: """
+		(
+		find . -name '*.cue' -print0 | xargs -0iX dirname X | sort -u | {
+			while read -r dir; do
+				[ "$(basename $dir)" = "cue.mod" ] && continue
+				echo "--- $dir"
+				cue eval "$dir" >/dev/null
+			done
+		} > /out 2>/err
+		) || true
+		"""
+}
+
+result: (os.#File & {
+		from: ctr.ctr
+		path: "/out"
+}).contents @dagger(output)
+
+err: (os.#File & {
+		from: ctr.ctr
+		path: "/err"
+}).contents @dagger(output)
+
+#CueCLI: {
+	command: string
+	ctx:     dagger.#Artifact
+	vendor: [name=string]: dagger.#Artifact
+
+	ctr: os.#Container & {
+		image: alpine.#Image & {
+			package: {
+				curl: true
+				tar:  true
+			}
+		}
+		setup: [
+			"""
+				set -e
+				cd $(mktemp -d)
+				curl -L https://github.com/cue-lang/cue/releases/download/v0.4.0/cue_v0.4.0_linux_amd64.tar.gz -o cue.tgz
+				tar zxvf cue.tgz
+				cp cue /usr/local/bin/cue
+				rm -fr ./*
+				""",
+		]
+		mount: "/ctx": from: ctx
+		for name, dir in vendor {
+			mount: "/ctx/cue.mod/pkg/\(name)": from: dir
+		}
+		dir:       "/ctx"
+		"command": command
+	}
+}