fix: pressing shift or control key in FluentListBox toggles the selection

[jpmikkers]

🐛 Bug Report

Pressing the shift or control key in a manually filled FluentListBox toggles the selection.

💻 Repro or Code Sample

See the first sample here, select one item with a mouse, then press the shift or control key. Keeping the shift key pressed shows the selection indicator toggling rapidly. Tested in firefox 131.0.3 and Edge 129.0.2792.89 https://www.fluentui-blazor.net/Listbox

🤔 Expected Behavior

The control and shift key are modifiers, I don't expect them to directly toggle selections but only in combination with other keys.

😯 Current Behavior

Shift or Control toggles the selection indicator.

💁 Possible Solution

N/A

🔦 Context

While using a list people will try holding the shift key to do multiple selection, the rapid toggling that occurs here looks a bit odd.

🌍 Your Environment

Windows 11 24H2 Tested in firefox 131.0.3 and Edge 129.0.2792.89 FluintUI blazor site Version: 4.10.2+0bbc884e - Powered by .NET 9.0.0-rc.2.24473.5