feat: add sync variant

[ematipico]

Changes

Closes #10876

I added a "sync" variant to the command. This will be useful to the extension too.

This is flagged as minor, because it adds new information.

Testing

Existing CI should pass. Should I create a test? 🤔

Docs

withastro/docs#9110

[changeset-bot]

🦋 Changeset detected

Latest commit: d5ba3eb

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

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[github-actions]

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

[florian-lefebvre]

LGTM, may break a few integrations

[ematipico]

LGTM, may break a few integrations

How? :|

Maybe because they use a switch of command?

[florian-lefebvre]

yes, command have been holding 3 possible values for so long that maybe some conditions will be broken. That being said, I don't see a better way than this so up to integrations authors to update

[sarah11918]

Quick suggestion for the changeset @ematipico ! When something new is added, I always like starting with "Adds" because that's the biggest clue that this is new, something you could check out, but not necessary and shouldn't break anything.

Also, I saw the conversation here about whether or not some projects might be relying on the fact that there have been exactly three options previously. If you felt it was necessary or helpful, you could consider adding another paragraph with a single line just saying something like:

If your integration previously relied on knowing how many variants existed for the `command` property, you must update your logic to account for this new option.

if you feel like that's a common enough thing!

[florian-lefebvre]

I think it's useful to add such paragraph

[sarah11918]

Approving for docs!

merge day