TransformerMetaHighlightOptions.zeroIndex: support zero-index line numbers

[olets]

Clear and concise description of the problem

I'm migrating/upgrading a project from eleventy-plugin-shiki-twoslash to @shikijs/markdown-it. The project makes extensive use of meta highlight notation

```lang {i…}
```

transformerMetaHighlight https://shiki.style/packages/transformers#transformermetahighlight works well as a replacement… almost.

The older tools used 0-indexed lines.

```js {1}
not highlighted
highlighted
```

transformerMetaHighlight uses 1-indexed lines

```js {1}
highlighted // unexpected
not highlighted // unexpected
```

Suggested solution

Teach transformerMetaHighlight a new option zeroIndexed.

Alternative

No response

Additional context

Easy to imagine that others will hit this pain point when upgrading, and/or prefer to use 0-indexed line numbers.

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

Contributes

• If this feature request is accepted, I am willing to submit a PR to fix this issue