feat: loading screen

[Atinux]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

When running nuxt, you won't be able to access the url until the resources are available. This is really frustating and can also display this kind of error:

After working with @pi0, we introduce a loading screen for Nuxt, a GIF is way better to understand 😄
Note: I am using the -o option at the end to automatically open the browser window

Checklist:

• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[manniL]

Some feedback ☺️

addressed

[pi0]

loading-screen moved to its own dedicated repository (because of packaging requirements)

https://github.com/nuxt/loading-screen

Thanks to @egoist for poi tool.

[Atinux]

I also updated the nuxt loading indicator for SPA:

It supports a theme key to 'dark' for the dark background :)