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/go/values.yaml

@@ -0,0 +1,27 @@
+plan:
+    package: ./go/tests
+name: go
+inputs:
+    TestData:
+        dir:
+            path: ./go/tests/testdata
+sops:
+    kms: []
+    gcp_kms: []
+    azure_kv: []
+    hc_vault: []
+    age:
+        - recipient: age1gxwmtwahzwdmrskhf90ppwlnze30lgpm056kuesrxzeuyclrwvpsupwtpk
+          enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBpQ2o5dkg3S2tVZkhJZXoz
+            VWlmMjdvZ1B6VTB2SlhsNEdBUG5sT2xTZ2d3CnlUL1JHMW8yK0FkQTFra0tSMjJH
+            eTcrZUs3Y2lrUG9xUDgxNkhMa2VNbVUKLS0tIHowR2ZneG5nOUppQlY4N2hEZU9n
+            R0o3dlptazJPTmp3OFo5RDcxOVg1VVkK1lLu/wrPvgzXa8Ym3qdvcuYCj8csbtOG
+            T4HjRvA0EEF8jmFEuqS8Y/N0vQiezoZR7JU9PbjOoD1B5bLHtJcryQ==
+            -----END AGE ENCRYPTED FILE-----
+    lastmodified: "2021-07-08T09:54:38Z"
+    mac: ENC[AES256_GCM,data:hxLn6KQKeN0l1UlVVmOGA6IRsNA97xyeUBvbNjquqmF6+ess7l/oORRjZMNEgk7OnIC3Cjh6AlSph3iL4Jf9AWRBmsoyoQxb1njJNIotMyjveu3DcgV264U5HLGIUn0F3xncOxsGIAobLUjS4gTtP7wV2C9BV/X18cYfc9Ak4L8=,iv:H7hYoekofXOcyWzcnEWnYSlB3MvO3N+RqO3PrNIGGFE=,tag:Z4BNSUSLOUpmrZDyuTeV1Q==,type:str]
+    pgp: []
+    encrypted_suffix: secret
+    version: 3.7.1