Restore previous samples for lowpass filter on restart

This is a feature request to have the filter sensor restore it’s state and/or previous samples when restarting/reloading. I am not sure if restoring the state is also required to make this work, but I guess so.

Ref.: Lowpass filter "resets" on restart

Example config, even though the specific config values does not matter for the general behavior observed.

      - filter: lowpass
        time_constant: 5
        precision: 4

A couple of screenshots of current results for the filter sensor with a lowpass filter.
Blue is the lowpass filter, restarts on the red arrows: