fix: dev cmd didn't watch files due to import mangling

Appearently the esModuleInterop flag in TypeScript is not compatible
with node-watch, and the import helper was mangling the import as a
result and causing an error in the dev command that resulted in files
not being watched.

This fixes that import issue and adds an e2e test to help prevent a
regression of this issue in the future.

test/run-e2e.ts

@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { fork } from "child_process";
+import * as fs from "fs";
+import * as path from "path";
+
+import { shuffle } from "./lib/utils";
+
+const TEST_SUITES_DIR = path.join(__dirname, "e2e");
+const files = fs.readdirSync(TEST_SUITES_DIR);
+// Shuffle test suites to detect ordering dependencies between them.
+shuffle(files);
+for (const file of files) {
+    const fullPath = path.join(TEST_SUITES_DIR, file);
+    fork(path.relative(process.cwd(), fullPath)).on("exit", (code) => {
+        if (code !== 0) {
+            process.exitCode = 1;
+        }
+    });
+}