Support line highlighting for Docusaurus via code-line-numbers

[eitsupi]

Description

It would be great if the following line highlighting that Quarto supports in revealjs format also worked in Docusaurus.

```{.python code-line-numbers="6-8"}
import numpy as np
import matplotlib.pyplot as plt

r = np.arange(0, 2, 0.01)
theta = 2 * np.pi * r
fig, ax = plt.subplots(subplot_kw={'projection': 'polar'})
ax.plot(theta, r)
ax.set_rticks([0.5, 1, 1.5, 2])
ax.grid(True)
plt.show()
```

https://quarto.org/docs/presentations/revealjs/index.html#line-highlighting

The syntax on Docusaurus is like this:

```jsx {1,4-6,11}
import React from 'react';

function MyComponent(props) {
  if (props.isBar) {
    return <div>Bar</div>;
  }

  return <div>Foo</div>;
}

export default MyComponent;
```

https://docusaurus.io/docs/markdown-features/code-blocks#highlighting-with-metadata-string

The problem here is that revealjs is hard-coded in the following part where this conversion is performed, and other formats cannot be added later.
It would be great if third party formats could enable this feature.

quarto-cli/src/resources/filters/quarto-pre/line-numbers.lua

Lines 13 to 16 in 880565f

	-- remove for all formats except reveal
	if not _quarto.format.isRevealJsOutput() then
	el.attr.attributes["code-line-numbers"] = nil
	end

[cderv]

Thanks for the idea. I think this is easy enough to implement. I'll have a look.

[cderv]

Tracked now in

• Support line highlighting for Docusaurus via code-line-numbers #7201