Qt6 allows us to set the RHI backend, however QQuickWidget is only
supported when using OpenGL. QWebEngineView instantiation uses
QQuickWidget and isn't required as we wish to use the previewengine
in a headless mode. So it can just be based on QWebEnginePage.
Change-Id: If05ca5c89272704b54c29318803c8773984b087c
Introduces a primitive QML ListView based chat view lacking
features present in the previous web chat view, that will be added
in subsequent commits(styling, preview/media/link/file-transfer
message type support, etc.).
Gitlab: #467
Change-Id: Iedc40f6172a6cdacc48cda6f4187053fbf226713