The current `@nx/react:app` generator does not take the `--js` option
into account. There are two problems:
1. `index.html` includes `main.tsx` not `main.jsx`.
2. `.js` files with JSX are invalid in Vite, and must be named `.jsx`.
This PR adds a new option to the `toJS` devkit util to preserve `.jsx`
rather than renaming them to `.js`. The vast majority of non-Vite React
projects will use `.js` and not `.jsx` (e.g. Next.js, Expo, Remix, etc.)
so we just want to apply this change to Vite only for now.
In the future we could enhance React generators to support `--jsx`, for
example.
## Current Behavior
<!-- This is the behavior we have today -->
## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
-->
## Related Issue(s)
<!-- Please link the issue being fixed so it gets closed when this is
merged. -->
Fixes#20810
