fix: tab shortcut always returns true in listitem

[halil-pan]

Changes Overview

When I click tab on listItem or taskItem, the default sinkListItem command is executed and the result is returned. When sinkListItem returns false, the browser default behavior is automatically triggered, such as focusing on input on the page.

Implementation Approach

In the shortcut key handling function of listItem, always returns true for tab-related events, preventing subsequent behavior of the event

Verification Steps

1. Open preview page: local or online
2. Select the first line of any list
3. Click tab, before, the page will automatically jump to the taskItem position, after this change, nothing will happen.

Checklist

• I have renamed my PR according to the naming conventions. (e.g. feat: Implement new feature or chore(deps): Update dependencies)
• My changes do not break the library.
• I have added tests where applicable.
• I have followed the project guidelines.
• I have fixed any lint issues.

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[nperez0111]

We appreciate your contribution.

Unfortunately, this would break browser default behavior that may be depended on in other editor implementations.

And, it not returning true is by design so that other events may be triggered by the same keystroke.

So for that reason, I'm closing this PR. If your editor needs this behavior we encourage you to extend the extension & add that behavior yourself