Add support for PCF8574 and PCF8575 I2C port expanders

[H3wastooshort]

Describe the solution you'd like
Add simulation support for the PCF8574 port expander. Talking to them via I2C relatively simple and probably wont be too hard to implement.

Datasheets: PCF8574 PCF8575

[urish]

Thanks for the detailed request, I appreciate including the data sheet links.

I opened the request for voting.

In the meanwhile, it's possible to implement these chips using the custom chip API (#301).

@arcostasi even did a proof of concept for the PCF8574, but the code is outdated and uses an older version of the Custom Chip API, so it needs some extra work before it's usable again.

[laldana73]

The proof of concept for the PCF8574 is working now here