[feat] Compiler option css: 'none' support

[maxiruani]

Why?

I found that generating client side hydratable code with css: false or css: true end up processing styles entirely unnecessary.
When hydrating SSR components, the styles are commonly already generated and there is no need to generate it again for the client side bundle.
This will speed up the build development process because it completely avoids processing it.

Details

• I have also added support for more descriptive 'injected' (formerly true) and 'external' (formerly false) css option values. It still supports boolean values but it raises deprecated warning.
• Added support for 'none' css option.
• Added test for css: 'none' option.

References

• [feat] Compiler option css: 'none' support #7890 Old corrupted PR.
• rename compiler css option #7270 rename compiler css option
• esbuild-svelte skipCss proposal

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• Prefix your PR title with [feat], [fix], [chore], or [docs].
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with npm test and lint the project with npm run lint

[maxiruani]

@benmccann Thanks for the advice. It should be fine now. Let me know if you need anything else from me.

[benmccann]

@maxiruani it looks like this PR needs a rebase

[baseballyama]

LGTM. But I think we need to update the document.
https://svelte.dev/docs#compile-time-svelte-compile

[maxiruani]

@maxiruani it looks like this PR needs a rebase

Hi @benmccann, sorry for the delay, I've been on vacations. Does the PR still needs a rebase?

[benmccann]

Yes, this PR still needs to be updated. You can see that it says "This branch has conflicts that must be resolved". And the docs should be updated as @baseballyama suggested

[maxiruani]

@benmccann I think it should be fine now. Sorry for the trouble 😄. Let me know if you need anything else from me.
Thanks!