Add mkdir task tests

Signed-off-by: Vasek - Tom C <tom.chauveau@epitech.eu>

tests/tasks/mkdir/mkdir.cue

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"alpha.dagger.io/europa/dagger/engine"
+)
+
+engine.#Plan & {
+	actions: {
+		image: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+
+		mkdir: engine.#Mkdir & {
+			input: image.output
+			path: "/test"
+		}
+
+		writeChecker: engine.#WriteFile & {
+			input:    mkdir.output
+			path:     "/test/foo"
+			contents: "bar"
+			mode:     700
+		}
+
+		readChecker: engine.#ReadFile & {
+			input: writeChecker.output
+			path: "/test/foo"
+		} & {
+			// assert result
+			contents: "bar"
+		}
+	}
+}