Add soft takeover mode for MIDI CC binding

[riban-bw]

Is your feature request related to a problem? Please describe.
When an absolute MIDI CC controller (like a pot or slider) is bound to a zynthian control, any change of CC will cause the control to jump to the CC value immediately.

Describe the solution you'd like
It would be advantageous to add a soft takeover mode. This would not change the control value until the CC value had passed sufficiently close to its current value to assume the knob or slider had been moved to the right value. If CC values are received that are either side of the current value then we can assume it has passed through the current value and take over. If the CC value is sufficiently close (maybe +/-10) then we can assume we are close enough and take over.

It would be good to show an indication of the polarity and distance of CC value from control value, e.g. show the CC value as another, thinner, different coloured ring or marker. It may even be advantageous to always show such a marker (not just whilst in soft takeover) which could give user an indication that the control is being adjusted remotely via CC.

Describe alternatives you've considered
This is a new feature that is implemented in other systems, e.g. Fostex Mixtab so I don't have an alternative. I just think this would be a good feature.

Additional context
Soft takeover is sometimes called "catch" or "wait to match".
It may be advantageous to allow the user to enable / disable this feature either globally or per control or per MIDI controller or per MIDI CC.

[riban-bw]

This is a duplicate of issue #724 but I think this report has better info so will close #724.