Fix scrolling of the chat view at expense of some more memory usage.

[manyoso]

This is using https://doc.qt.io/qt-6/qml-qtquick-listview.html#cacheBuffer-prop to actually be able to scroll the chatview. I'm at a loss for how Qt developers thought not using this would be acceptable in nearly any circumstance? Why wasn't this the default??

Before:

After: