Increase analog input support in Pro Micro and Nano

[JaimeLeon2]

Is your feature request related to a problem? Please describe.
The Pro Micro and Nano boards have 9 and 8 analog capable pins respectively, but are limited in Mobiflight to only 5 and 6 analog inputs. I propose to increase the Mobiflight limit to each board's true capacities.

Describe the solution you'd like
Increase the number of analog inputs in Pro Micro to 9.
Increase the number of analog inputs in Nano to 8.

Describe alternatives you've considered
Only alternative is to use more boards. This is not feasible in throttle quadrants where space is typically limited and use of many potentiometers is needed.

Additional context
It seems potentiometers are very pin efficient, just requiring one pin to function. There are ways to use more analog input in rotary switches and groups of buttons, attaching resistors in series.

[DocMoebiuz]

@neilenns, @elral - can somebody take this one on?

[neilenns]

Not until next weekend at the earliest, sorry :(

[elral]

I can do it after I will be back tomorrow.
We have to consider the device buffer usage as AnalogIn has a high memory consumption.