Add support for collapsible details sections

[TryCatch22]

Issue description

GitHub's built-in markdown renderer (as used for many README.md files) supports collapsible details sections. Can we have that same support implemented in MarkdownViewer++?

Markdown to reproduce

<details>
    <summary>Click me for more details</summary>

    Here is a more detailed explanation, hidden in this collapsible section.

</details>

Environment

• Notepad++ 8.4.8 (x64)
• MarkdownViewer++ 0.8.2
• Windows 10 (x64)

[TryCatch22]

Here is a working example: https://gist.github.com/pierrejoubert73/902cc94d79424356a8d20be2b382e1ab

[DGrothe-PhD]

As a workaround, if you have VSCode installed, you can view your markdown files with extension vscode-markdown-pdf.