Fix expanding networks in Chat Monitor settings

Fix expanding networks in Chat Monitor settings

Update the network expanded/collapsed state when setting a model,
including filtered models.

This fixes the Chat Monitor settings page not updating the expanded
and collapsed networks on first load.  It might be excessive to apply
on every model change; if performance issues arise, it can be moved
to BufferView::setFilteredModel() or elsewhere.

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Resolves GH-271.