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/alpine/values.yaml

@@ -0,0 +1,23 @@
+plan:
+    package: ./alpine/tests
+name: alpine
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1gxwmtwahzwdmrskhf90ppwlnze30lgpm056kuesrxzeuyclrwvpsupwtpk
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSB0Ky9vQU16Vms0OUpOaVBk
+            K3J5R1RqREwvTEdYenVJaEl0VDB2aXJ0QTBrCnM2QnhUa0hXS0tGUjRvMnlveUZT
+            UitUU2lwUHBGUXVmbms1R2srdW1iSGMKLS0tIFExMzh6WlowVUNzRDR2Rkx0MXh0
+            N0JOK1FwdzkrcGR5V0xhUDdNOFNvYk0KetOvulxA0Hilyhv+eWBqYO3GXNvm38Y1
+            9Pa7HYazNyi0qMcZpecWlp4QsOoL876dj1rE62cYHT2hkt2J2ijAUw==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2021-07-08T09:51:43Z"
+    mac: ENC[AES256_GCM,data:5ApIUpcKaDi3UXL9jyeDBSJJw//BZE2eFZxsuCHVRNyR48FBGj7Wn0Ned2shZ6wNsKcZt5TpxdVILc8SEWwJ9NXeAFuTUZqCZypmDBxGdpo1M5eW0xRAEXQ6UpkG2+2uM0hHCEh8rECcvj0zGHMKgrbXOZt+iyeDuMBMME/V58w=,iv:qWCxgIuVD1RMDrWYgzUSK/KNxS85cJONsV0CzsHf/UU=,tag:NEJM7oZmHXn3ujS2zoN1EA==,type:str]
+    pgp: []
+    encrypted_suffix: secret
+    version: 3.7.1