refactor: simplify rollup config and match @tauri-apps/api output style (#722)

* refactor: simplify rollup config and match `@tauri-apps/api` output style

* add license headers

* update api-iife.js [skip ci]

---------

Co-authored-by: Lucas Nogueira <lucas@tauri.app>

plugins/shell/rollup.config.js

@@ -0,0 +1,22 @@
+// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
+import { createConfig } from "../../shared/rollup.config.js";
+import { nodeResolve } from "@rollup/plugin-node-resolve";
+import typescript from "@rollup/plugin-typescript";
+import terser from "@rollup/plugin-terser";
+
+export default createConfig({
+  additionalConfigs: {
+    input: "guest-js/init.ts",
+    output: {
+      file: "src/init-iife.js",
+      format: "iife",
+    },
+    plugins: [typescript(), terser(), nodeResolve()],
+    onwarn: (warning) => {
+      throw Object.assign(new Error(), warning);
+    },
+  },
+});