stdlib: move core definitions to engine package

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

stdlib/dagger/dagger.cue

@@ -3,18 +3,9 @@ package dagger
 
 import (
 	"alpha.dagger.io/dagger/op"
+	"alpha.dagger.io/dagger/engine"
 )
 
-// A reference to a filesystem tree.
-// For example:
-//  - The root filesystem of a container
-//  - A source code repository
-//  - A directory containing binary artifacts
-// Rule of thumb: if it fits in a tar archive, it fits in a #FS.
-#FS: {
-	_fs: id: string
-}
-
 // An artifact such as source code checkout, container image, binary archive...
 // May be passed as user input, or computed by a buildkit pipeline
 #Artifact: {
@@ -24,17 +15,8 @@ import (
 	...
 }
 
-// A reference to a network service endpoint, for example:
-//  - A TCP or UDP port
-//  - A unix or npipe socket
-//  - An HTTPS endpoint
-#Service: {
-	_service: id: string
-}
-
 // Dagger stream. Can be mounted as a UNIX socket.
-// FIXME: Deprecated. For backward compatibility only, use #Service instead.
-#Stream: #Service
+#Stream: engine.#Service
 
 // A reference to an external secret, for example:
 //  - A password
@@ -42,9 +24,7 @@ import (
 //  - An API token
 // Secrets are never merged in the Cue tree. They can only be used
 // by a special filesystem mount designed to minimize leak risk.
-#Secret: {
-	_secret: id: string
-}
+#Secret: engine.#Secret
 
 #Input: {
 	@dagger(input)

stdlib/dagger/engine/fs.cue

@@ -0,0 +1,11 @@
+package engine
+
+// A reference to a filesystem tree.
+// For example:
+//  - The root filesystem of a container
+//  - A source code repository
+//  - A directory containing binary artifacts
+// Rule of thumb: if it fits in a tar archive, it fits in a #FS.
+#FS: {
+	_fs: id: string
+}

stdlib/dagger/engine/plan.cue

@@ -1,4 +1,4 @@
-package dagger
+package engine
 
 // A deployment plan executed by `dagger up`
 #Plan: {

stdlib/dagger/engine/secret.cue

@@ -0,0 +1,11 @@
+package engine
+
+// A reference to an external secret, for example:
+//  - A password
+//  - A SSH private key
+//  - An API token
+// Secrets are never merged in the Cue tree. They can only be used
+// by a special filesystem mount designed to minimize leak risk.
+#Secret: {
+	_secret: id: string
+}

stdlib/dagger/engine/service.cue

@@ -0,0 +1,9 @@
+package engine
+
+// A reference to a network service endpoint, for example:
+//  - A TCP or UDP port
+//  - A unix or npipe socket
+//  - An HTTPS endpoint
+#Service: {
+	_service: id: string
+}