Nested unordered lists throw an accessibility warning

Describe the bug
Nested unordered lists trigger an accessibility error when using the Accessibility Insights extension and running a FastPass.

This issue exists in both the latest version of RoosterJS, and in the version we are using for the text editor in our component library (8.61.0).

When adding a nested unordered list, the HTML renders as:

<ul>
    <li>first</li>
    <li>second</li>
    <ul>
        <li>indent one</li>
        <li>indent two</li>
    </ul>
    <li>third</li>
</ul>

According to W3, nested lists should be formatted as:

<ul>
    <li>first</li>
    <li>second
        <ul>
            <li>indent one</li>
            <li>indent two</li>
        </ul>
    </li>
    <li>third</li>
</ul>

The above will not trigger a warning using the FastPass in the Accessibility Insights extension.

Here is the error from FastPass for the latest version of RoosterJS:

Title: WCAG 1.3.1: Ensure that lists are structured correctly (ul)
Tags: Accessibility, WCAG 1.3.1, list

Issue: Ensure that lists are structured correctly (list - https://accessibilityinsights.io/info-examples/web/list)

Target application: RoosterJs Demo Site - https://microsoft.github.io/roosterjs/index.html#

Element path: #RoosterJsContentDiv > ul

Snippet: <ul data-editing-info="{&quot;applyListStyleFromLevel&quot;:true}" style="list-style-type: disc;">

Related paths: 
  ul > ul

How to fix: 
Fix all of the following:
  List element has direct children that are not allowed: ul

Environment: Microsoft Edge version 135.0.0.0

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This accessibility issue was found using Accessibility Insights for Web 2.46.0 (axe-core 4.10.2), a tool that helps find and fix accessibility issues. Get more information & download this tool at http://aka.ms/AccessibilityInsights.

To Reproduce
Steps to reproduce the behavior:

1. Go to the Rooster JS Demo page
2. Click on the Unordered List menu button
3. Type a couple bullet points
4. Hit the tab key to add a nested unordered list
5. Type a couple bullet points
6. See the error that the rendered HTML adds a ul as a sibling of the li elements instead of as a child of a li element.

Device Information

• OS: Mac
• Browser: Edge
• Version: 135

Start from the Unordered List menu behavior on the RoosterJS Demo page and reproduce the nested-list case with Accessibility Insights FastPass. Trace the list-editing entry point that handles Tab indentation; done means the nested ul is contained within its parent li and the reported WCAG 1.3.1 warning no longer appears.