add support for attribute {.scala} to verbatim text

[michelou]

@abgruszecki Scala3doc currently supports the following Markdown syntax for code blocks :

```scala
val x = 1
```

Can you please validate that Scala3doc does also support the following two Markdown syntaxes (see discussion in PR #10953) ?

1. Code block with attribute {.scala}, for instance :

```{.scala}
val x = 1
```

2. Verbatim text with attribute {.scala}, for instance :

Given the dedinition `val x = 1`{.scala}

Goal: display the same Scala syntax hightlighting both in code blocks and in verbatim texts.

[abgruszecki]

I agree it'd be useful for inline monospace and code blocks to have the same support for highlighting. We probably should take a look at some extensions to Markdown that support that sort of syntax.

/cc @romanowski