[feat] auto shim `import.meta.url` for cjs output

Like rollup, it shims `import.meta.url` with the following codes:

```js
(typeof document === 'undefined' ? require('u' + 'rl').pathToFileURL(__filename).href : (document.currentScript && document.currentScript.src || new URL('test.js', document.baseURI).href))
```

Additionally, there is an official rollup plugin [`@rollup/plugin-esm-shim`](https://github.com/rollup/plugins/tree/master/packages/esm-shim) which adds `__filename`, `__dirname`, `require` support for ESM automatically, maybe it can be adapted as an esbuild plugin also.

No esbuild files or tests are named in the issue. Start by locating the transform for import.meta.url when emitting CommonJS and compare Rollup's esm-shim behavior. Done means CommonJS output automatically provides the requested import.meta.url-compatible value in the relevant environments.

Written by the indexing model from the issue text.