AK3: add support for simple init_boot + vendor_kernel_boot setup

- starting with Pixel 7 series, boot_img_hdr_v4 is now even more complicated, adding 2 more new partitions (init_boot and vendor_kernel_boot) so let's attempt to keep it as simple as we can
- if init_boot partition is detected split up flash files for boot (kernel), init_boot (ramdisk), and vendor_kernel_boot (dtb)
- continue to support current practice of Image* and dtb in zip root by automatically creating a multi-partition AK3 zip setup from these files (ramdisk directory is for the init_boot partition since that's where Magisk and overlay.d will be)

NOTE 1: anykernel.sh must still be setup for multi-parition patching - see the updated Example file for parts to uncomment
NOTE 2: currently magiskboot still does not support unpack/repack of VNDRBOOT v4 multi-ramdisk format (i.e. vendor_boot v4 and vendor_kernel_boot) so if modifications are necessary in these ramdisks they will need to be prebuilt and flashed whole by including vendor_boot.img and/or vendor_kernel_boot.img in the zip root

META-INF/com/google/android/updater-script

@@ -3,4 +3,4 @@
 # Dummy file; update-binary is a shell script (DO NOT CHANGE)
 #
 #
-# AK_BASE_VERSION=20221019
+# AK_BASE_VERSION=20221111