feat: make sass optional and support sass-embedded

[Mister-Hope]

sass-loader v16 prefer sass-embedded with modern api, and vite 5.4 supports modern api as well.

So we want to use sass-embedded with modern-compiler to improve sass performance.

[Mister-Hope]

Webpack ci are all falling, could you help to investigate?

[pengzhanbo]

Webpack ci are all falling, could you help to investigate?

I investigated the issue for a while and can only confirm that the problem is caused by plugin-pwa, as the vuepress build completes but the process does not terminate.

I suspect that the issue lies with this line of code pwaPlugin.ts#L71, as commenting it out allows the process to successfully terminate upon repeated execution. However, when building the project without the directories e2e/.vuepress/{.cache,.temp,dist}, the process does not terminate.

This confuses me; I am not clear about what happened to cause it.

It is important to note that when I switched back to the main branch and executed e2e:build-webpack, it worked fine, so it is very likely that the issues are due to dependency upgrades in this branch.

[Mister-Hope]

@meteorlxy any ideas?