SelectedItemChanged doesn't trigger on first sub item

[stefandhondt]

Given your exact example code for the Treeview with unlimited items located at https://www.fluentui-blazor.net/TreeView#withunlimiteditems, the first subitem of an item never gets selected. All other items will update SelectedItem, but never the first.

[dvoituron]

Will be fixed in the next release: #2414