Fix regression where webpack doesn't permit importing scss/css

[tagliala]

Add some entries to package.json to improve compatibility with webpack

• Add default style and sass exports as per webpack requirements
• Add public/assets/styles/* exports for CSS files
• Add src/styles/* exports for Scss files. Extension can be omitted to prevent linting issues with stylelint
• Add *.scss and *.css to "side effects" to prevent issues with tree-shaking

With this commit, it is possible to import styles with the same syntax of v10 to prevent a breaking change in webpack based applications

Refs:

• https://webpack.js.org/guides/package-exports/ -

Close #1184

Description

Screenshots (if appropriate)

Types of changes

• Chore (tooling change or documentation change)
• Refactor (non-breaking change which maintains existing functionality)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• My code follows the code style of this project.
• I have added new tests for the bug I fixed/the new feature I added.
• I have modified existing tests for the bug I fixed/the new feature I added.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[tagliala]

@Xon here it is my attempt to fix this issue. I'm using the forked branch at the moment and it works.

Sorry, but I really struggle a lot with all this webpack / node / exports things. I've tried hard at the best of my knowledge

What allows to make the import work like before are just the three extra exports:

    "./public/assets/styles/*.css": "./public/assets/styles/*.css",
    "./src/styles/*.scss": "./src/styles/*.scss",
    "./src/styles/*": "./src/styles/*.scss"

I've added also style and sass for completeness, but in example including choices.js in a scss file pre-processed by sass-loader and css-loader, will result in including the style instead of the sass export, so I'm not sure what they are about

About sideEffects, I'm seeing that often they include .css, so maybe it is good to have. This matches your PR to fix the issue

[Xon]

Looks good, I'll update the documentation around this