fix test-site: CRA/webpack file extension issue (#37)

test-site was broken with the following errors:
<img width="1703" alt="Screenshot 2023-08-30 at 3 28 12 PM" src="https://github.com/yext/chat-ui-react/assets/36055303/540c67b8-0358-4069-b7e9-2c0fe52fcb3c">
specifically this error:
```
Module not found: Error: Can't resolve './components' in '/Users/ytruong/chat-ui-react/lib/esm/src'
Did you mean 'index.js'?
BREAKING CHANGE: The request './components' failed to resolve only because it was resolved as fully specified
(probably because the origin is strict EcmaScript Module, e. g. a module with javascript mimetype, a '*.mjs' file, or a '*.js' file where the package.json contains '"type": "module"').
The extension in the request is mandatory for it to be fully specified.
Add the extension to the request.
```

This is due to CRA 5 (create-react-app v5) internally using webpack 5, which follows the Node.js module resolution algorithm and it requires specifying the file extension. In this case, adding `"type": "module"` in previous CR triggers this rule in webpack https://webpack.js.org/configuration/module/#resolvefullyspecified. This is a known issue in CRA 5: facebook/create-react-app#11865.

For vite/pages, pagesJS get around this using `--experimental-specifier-resolution=node` flag: https://github.com/yext/pages/blob/main/packages/pages/src/bin/spawn.ts#L19-L25

This PR implements a workaround to disable this webpack behavior using `craco` to update the webpack config without ejecting the CRA app.

J=CLIP-450
TEST=manual

see that test-site works again
<img width="1358" alt="Screenshot 2023-08-30 at 3 31 04 PM" src="https://github.com/yext/chat-ui-react/assets/36055303/6a48a76b-23f8-4715-8186-4a28f8961a8d">

test-site/craco.config.js

@@ -0,0 +1,19 @@
+module.exports = {
+ webpack: {
+ configure: {
+ module: {
+ rules: [
+ //This rule is to escape the error of requiring .mjs/.js extension due
+ //to origin being strict ESM (package.json contains '"type": "module"')
+ //https://webpack.js.org/configuration/module/#resolvefullyspecified
+ {
+ test: /\.m?js$/,
+ resolve: {
+ fullySpecified: false,
+ },
+ },
+ ],
+ },
+ },
+ },
+};