Draft: main/checkra1n: new aport

Already tried to submit this to Alpine upstream but it got rejected.

checkra1n is a tool to trigger an exploit on various Apple devices. It is useful for the postmarketOS project to access the custom bootloader pongoOS on iPhone 7, from where one could boot Linux. I would like to use this tool in an automated way with pmbootstrap flasher boot, see MR here.

aports upstream didn't accept it because it is not yet open source. The developer plan to open source it but there is no release date yet. To avoid issues with redistribution, this package just includes a script which downlaods the current version, checks the file checksum and runs it.

Hope we can have this here as long it is not officially open sourced.

Regards Jonas