feat: Add “use client” to fix React Server Components

[sawyerh]

Summary

This adds the "use client" directive to the transpiled JS module to support apps utilizing React Server Components:

Some context from the React docs on this directive:

When a file marked with 'use client' is imported from a Server Component, compatible bundlers will treat the module import as a boundary between server-run and client-run code.

For apps that use React Server Components, the app is server-rendered by default. 'use client' introduces a server-client boundary in the module dependency tree, effectively creating a subtree of Client modules.

Without this directive, apps attempting to use React Server Components are greeted with an error screen. See #2540.

I think this PR would be highly impactful to Next.js applications in particular, supporting the adoption of the new App Router and newer React features.

Additional context

I don't think this is the perfect solution to supporting React Server Components, but I think it's a quick fix. Longer term, #192 is likely a better approach, so that components without any React hooks or event listeners can be a server component.

Related Issues or PRs

• [fix] Issues properly using with the Next.js "App Router" architecture (server components) #2540

How To Test

1. Clone https://github.com/sawyerh/react-uswds-server-components-bug
2. npm install
3. npm run dev
4. Open http://localhost:3000/react-uswds and observe an error
5. Stop the dev server, then run: npm link @trussworks/react-uswds --save
6. Open http://localhost:3000/react-uswds and observe the error is gone

Screenshots

[sawyerh]

@brandonlenz Just checking in to see if this is a change y'all would be open to or if I should pursue an alternative. (Tagging you since you're listed in the readme as the active maintainer).

[brandonlenz]

I am good with this change. Looks like a quick win