Make view cvars such as `cl_rollspeed` persist across restarts

[Calinou]

This removes the need for creating an autoexec to define those cvars persistently, which is usually what's desired. This was already applied to some cvars like cl_rollangle, but not all of them.

See Xonotic's DarkPlaces fork which adopted a similar change recently: https://gitlab.com/xonotic/darkplaces/-/issues/393