europa: Code Embedding POC

WIP PoC for code embedding

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

tests/tasks/source/source.cue

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"dagger.io/dagger/engine"
+)
+
+engine.#Plan & {
+	actions: {
+		image: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+
+		source: engine.#Source & {
+			path: "."
+		}
+
+		exec: engine.#Exec & {
+			input: image.output
+			mounts: code: {
+				dest:     "/src"
+				contents: source.output
+			}
+			args: ["/src/test.sh"]
+		}
+
+		verifyHello: engine.#ReadFile & {
+			input: source.output
+			path:  "/hello.txt"
+		} & {
+			// assert result
+			contents: "hello\n"
+		}
+
+		verifyWorld: engine.#ReadFile & {
+			input: source.output
+			path:  "/world.txt"
+		} & {
+			// assert result
+			contents: "world\n"
+		}
+	}
+}