Implement wait gpio for idx >= 32

[jepler]

An instruction like wait 0 gpio N refers to the absolute GPIO number. sdk pioasm tracks which numbers have been used in 16-bit blocks, reporting an error if pins in the "low" and "high" ranges are both used. This is a bit funky and it's not clear what the behavior should be. sdk pioasm gives some weird results, which I reported as an issue: raspberrypi/pico-sdk#2141