netlify: Europa port

- Fix netlify.#Deploy (there's still FIXMEs)
- Externalize the `deploy.sh` script
- Add tests
- Misc engine fixes for more explicit error messages

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

pkg/universe.dagger.io/netlify/test/netlify.bats

@@ -0,0 +1,9 @@
+setup() {
+    load '../../bats_helpers'
+
+    common_setup
+}
+
+@test "netlify.#Deploy" {
+    dagger up ./netlify-test.cue
+}