Remove pins from Io

[bugadani]

This PR has two implications:

• Users who don't need to work with GPIO interrupts no longer have to construct Io
• Users who need to work with GPIO interrupts can now configure them even when pins are in use. Previously this was impossible because pins were moved out of Io so users could no longer call methods on it.

This is a slight variation on the idea originally raised by #2010 (comment)

Sorry, this touches literally every example we have.

[Dominaezzz]

LGTM

This caught my eye but I don't think it's important enough to change.

peripherals: [
    // comma separated
],
pins: [
    // not comma separated
]

(Mildly surprised the S2's GPIO alternative functions haven't been mapped out yet)

[bugadani]

This caught my eye but I don't think it's important enough to change.

I didn't want to mess with the macro syntax, this is a straight-up cut and paste.

[bjoernQ]

LGTM - lots of changes but a lot of that is unavoidable noise