Support PCF85263A #56
Description
See Neotron-Compute/Neotron-Pico#167. We may want to add support for this kind of RTC, which will be our third. The advantage is that it can be trimmed more accurately than the DS1307 or MCP7940.
How to expose the trim API is TBD. It might just need to be done through the existing I2C API.