feat!: mdc.config.js support, improve shiki bundle

[antfu]

Resolves #124

Changes

• Support mdc.config.ts/js file, imported via #mdc-configs
  • The interface looks like this: https://github.com/nuxt-modules/mdc/blob/feat/mdc-configs/src/config.ts
• With highlighter: 'custom', it allows users to provide a highlighter function (instead of filepath) to have custom highlight. In that case, Shiki won't be included in the bundle at all.
• Now the shiki instance is constructed with fine-grain bundle at build time; This allows MDC to only ships used languages/themes to the bundle, not all of them, making it works more efficient on edge. Accordingly, all languages need to be specified via highlighter.langs statically (it's a breaking change). highlighter.preload is deprecated.
  • The .output dist of the /playground comparison:
    • main branch: 22MB (4.5MB zipped)
    • this PR: 13MB (3.3Mb zipped)

Refactor

• Move templates to /templates folder.
• Refactored how highlighter is resolved.

TODOs

• Hooks to add config sources
• Passing code frame meta string to the pipeline
• Test compatibility with downstream Nuxt Content and ecosystem

[antfu]

This PR is ready to review. Also did a test on nuxt.com with: nuxt/nuxt.com#1486

[farnabaz]

From what I understand now, we switched to use WASM by default. This breaks module's usability in some use-cases.

We need to consider a couple of usages:

• MDC module should be able to parse & render contents in browser, with or without API
• MDC module could be used in non-Nuxt context, like Strapi API. We should propose a solution for those environments.
  • Importing getMdcConfigs from #mdc-configs will fail outside of Nuxt.
  • We need a way to pass mdcConfig into the parser function in this case

[antfu]

For WASM, Shiki/Shikiji always needs WASM, and the do works in the browser. This PR does not change that.

MDC in non-Nuxt context

Can you give a more concrete example of what the usages be like? I am happy to expose the necessary options to make them decoupled.

[farnabaz]

🚀