chore: update react-scripts to v5

[ericrallen]

Motivation

This updates react-scripts in the generated starter app from @datadog/create-app in order to resolve the react-error-overlay issue that was preventing hot reloading from working while developing an app after using yarn create @datadog/app.

References:

• v5 Regression react-error-overlay build - Uncaught ReferenceError: process is not defined facebook/create-react-app#11771
• https://stackoverflow.com/a/70452191/656011

Changes

Upgrade to v5.0.0 of react-scripts

Testing

To See the Current Issue

1. Clear yarn cache and run yarn create @datadog/app
2. Run yarn start in generated app
3. Make change to src/widget/index.tsx in generated app
4. Notice that hot reload does not work

To Test the Idea Behind This Fix

1. Delete node_modules and yarn.lock
2. Update react-scripts version in package.json to ^5.0.0
3. Run yarn
4. Repeat steps 2 & 3 from the To See the Current Issue above
5. Notice that hot reload does work

To Test this Fix:

1. Checkout this branch
2. yarn link the @datadog/create-app package
3. Run yarn create @datadog/app --commit 52f5e05d00077915e8a7ed424d4bd83ae6e1fe85
4. Run yarn start in generated app
5. Make a change to src/widget/index.tsx in generated app
6. Notice that hot reload does work
7. Shut down the development server
8. yarn unlink the @datadog/create-app package

Releases

Choose one:

• No release is necessary.
  If you're only updating examples/documentation, this is likely what you want.
• All packages that need a release have a changeset
  Only @datadog/create-app needs a release

[ericrallen]

Here's s screenshot of the previous behavior where the react-error-overlay <iframe> was blocking the DOM and preventing user interaction, too:

[joneshf-dd]

Sorry this broke on you. But, thanks for looking into it!

There's a bit more work before we can merge it. I tried to explain the situation and some ideas of what we can do, totally up to you what you'd like here.

[joneshf-dd]

This looks great! Thanks for going through this.

One last bit about bumping the packages. But as mentioned, if you'd prefer to avoid making more changes/dealing with versions, just merge it now and we'll follow-up on the version bumps before making the next release.

[joneshf-dd]

Thanks again for doing all this!