- running reset_ak before an unpack would remove any included ramdisk files from zip, so only remove if $split_img is detected suggesting an unpack has already occurred
- since magiskboot has built-in detection for the ChromeOS image pre-header signature, allow it to be auto-detected and if futility and signing files are present re-sign automatically (thanks @Zackptg5 for the nudge)
- simplify signing and error catching
- fix typo breaking ramdisk_recovery partition detection
- hide expected stderr for formats where some files may not exist (cmdline for ELF, etc.)
- previously this was failing a bit too spectacularly for my liking since $comp would erroneously get set to "fopen: ramdisk.cpio failed with 2: No such file or directory"
- on devices where there is no ramdisk.cpio unless rooted with Magisk this will indicate better to developers working on the device that they should be using "OG AK" mode to avoid trying to unpack a ramdisk which may or may not exist
- simplify rdtmp and $ramdisk creation and keep only in `unpack_ramdisk`
- fix `reset_ak` and `setup_ak` behavior if run before $block is set
- only save boot.img and boot-new.img in *-files subdirectories on multi-partition setups since otherwise the tmpfs (in recovery) and ext4 .img (when booted) size usage gets quickly out of hand
- fix slot_select=inactive when used with block=auto or block=boot partition detection
- the expected "cat: write error: No space left on device" gives a non-zero return code so always return true
- devices that flash dtbo abort since the return code would get passed back to the Backend and silently fail as the final command in anykernel.sh (via `write_boot`), so catch seperately with a proper error message for other image write methods
- some device recoveries (e.g. TWRP for wahoo) seem to have issues with the new `cat <image> /dev/zero > <block>` method of flashing, so allow setting customdd="bs=1048576" shell variable in anykernel.sh to work around this by reverting back to dd wipe+flash for dtbo as it does with boot
osm0sis