Light RTC_IO refactor

[Dominaezzz]

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Pull Request Details 📖

Description

cc @bugadani, let's design here.

I'm still trying to figure out the macro lol.

Testing

👀

[bugadani]

We should probably start by defining the InputSignal/OutputSignal equivalent. On the S3 there is no RTC_IO matrix, just alternate functions, so there are no numbered signals just yet, but on P4 there will be (9.13 LP Peirpheral Signal List).

This is mostly just generating two enums from metadata, and the GPIO matrix code could be a good enough template.