fix(lsp): markdown code fence should allow space before info string #24364

Problem:
Bash language server returns "hover" markdown content that starts with
a code fence and info string of `man` preceded by whitespace, which Nvim
does not render properly.

See https://github.com/bash-lsp/bash-language-server/blob/0ee73c53cebdc18311d4a4ad9367185ea4d98a03/server/src/server.ts#L821C15-L821C15
```typescript
function getMarkdownContent(documentation: string, language?: string): LSP.MarkupContent {
  return {
    value: language
      ? // eslint-disable-next-line prefer-template
        ['``` ' + language, documentation, '```'].join('\n')
      : documentation,
    kind: LSP.MarkupKind.Markdown,
  }
}
```

For example,
```
    ``` man
    NAME
       git - the stupid content tracker
    ```
```

If I remove the white space, then it is properly formatted. 
```    
    ```man instead of ``` man
```

Per CommonMark Spec https://spec.commonmark.org/0.30/#info-string
whitespace is allowed before and after the `info string` which
identifies the language in a codeblock.
> The line with the opening code fence may optionally contain some text
> following the code fence; this is trimmed of leading and trailing
> spaces or tabs and called the [info
> string](https://spec.commonmark.org/0.30/#info-string). If the [info
> string](https://spec.commonmark.org/0.30/#info-string) comes after
> a backtick fence, it may not contain any backtick characters. (The
> reason for this restriction is that otherwise some inline code would
> be incorrectly interpreted as the beginning of a fenced code block.)

 Solution:
 Adjust stylize_markdown() to allow whitespace before codeblock info.