`Page up` and `Page down` should also paginate

[bilogic]

Is your feature request related to a problem? Please describe. Up/Down keys currently can paginate when they reach the first or last message in the message list, however Page up and Page down only stays on the page.

Describe the solution you'd like Page up and Page down should also paginate for faster scrolling, e.g. when searching for a nearby date

Describe alternatives you've considered N/A

Additional context N/A