ported op.#FetchGit to engine.#GitPull

Signed-off-by: Richard Jones <richard@dagger.io>

tests/tasks.bats

@@ -93,3 +93,7 @@ setup() {
     "$DAGGER" --europa up ./scratch.cue -l debug
 }
 
+@test "task: #GitPull" {
+    cd "$TESTDIR"/tasks/gitPull/
+    "$DAGGER" --europa up ./exists.cue
+}

tests/tasks/gitPull/exists.cue

@@ -0,0 +1,10 @@
+package main
+
+import "alpha.dagger.io/europa/dagger/engine"
+
+engine.#Plan & {
+	actions: gitPull: engine.#GitPull & {
+		remote: "https://github.com/blocklayerhq/acme-clothing.git"
+		ref:    "master"
+	}
+}