Improve k6 Studio startup time

[going-confetti]

Feature description

Improve the UX of launching the application. Apart from reducing the startup time, we should think about the unhappy path (currently, the user is stuck with an non-dismissable splash screen if something goes wrong during the workspace initialization, for example)

Suggested solution (optional)

These are just ideas

• Code-splitting with React.lazy()
• modulepreupload
• Make the project structure setup an async task that completes after the app has launched?
• Check if we even need the splash screen
• TBD

The Electron docs list some options in the Performance Best Practices article.

Already existing or connected issues / PRs (optional)

No response