Move to shiki and stabilize dual themes support

[bluwy]

Changes

shikiji has been merged into shiki 1.0. This PR also moves back to shiki. There weren't any significant changes, so this PR is mainly package name change and small compat code added.

markdown.shikiConfig.experimentalThemes is also stabilized as markdown.shikiConfig.themes together with the move to shiki. It is not considered experimental by shikiji or shiki anymore.

Testing

Existing tests should pass

Docs

I've updated some links in the jsdoc to use the new site https://shiki.style. I've also made a docs PR: withastro/docs#6898

[changeset-bot]

🦋 Changeset detected

Latest commit: 4bdd901

The changes in this PR will be included in the next version bump.

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

This PR is blocked because it contains a minor changeset. A reviewer will merge this at the next release if approved.

[soerenmartius]

QQ: Wouldn't it make sense to add functionality such as decorators to the <Code/> component apo also?

[bluwy]

I guess we could too, along with transformers which is already supported in markdown.shikiConfig. I'm not sure what the current stance is for Code.astro since decorators and transformers are shiki-specific features, but I don't mind exposing it.

[soerenmartius]

I guess we could too, along with transformers which is already supported in markdown.shikiConfig. I'm not sure what the current stance is for Code.astro since decorators and transformers are shiki-specific features, but I don't mind exposing it.

That'd be awesome!

[CaptainOfPhB]

@bluwy @ematipico Can you fix conflicts and merge them into master? I can't wait to use the new Shiki :)

[bluwy]

I can fix them up later today, but this will only be merged for the next minor, which is scheduled some time next week. There shouldn't be any significant changes on the user-side though.

[sarah11918]

Approving this (and the accompanying docs PR) for docs!

Merge day