Add pio-based IncrementalEncoder on pi5

[jepler]

In rp1pio there is an example of using the pio peripheral to implement quadrature counting that doesn't require any CPU time.

We would like to see this code adapted into Adafruit_Blinka, and used instead of the thread-based implementation added in #937 when appropriate.

Benefits/limitations:

• uses the pio peripheral, which means no CPU time is required between polls
• very high polling rates above 1MHz can be used.
• Can count up to +-2 billion counts (full 32 bit signed counter)
• up to 4 encoders can be connected in this way (3 if neopixel is used)
• encoder pins for one knob must be adjacent
• only works on pi5 and only when rp1pio is installed and properly configured

[jepler]

ping @ladyada @makermelissa

[ladyada]

neat 🎛️

[makermelissa]

Awesome, I'll take a look and see if I can get that going.