Add mkfs.ext2 and mkfs.ext4 binaries to the android-recovery-installer

Using the unofficial TWRP for the Huawey Y530 (no official support yet) I encountered this issue:

+ make_ext4fs -L pmOS_root /dev/mapper/pm_crypt
/tmp/postmarketos/bin/pmos_install: line 1: make_ext4fs: not found

I have no idea where the make_ext4fs command comes from but the mkfs.ext4 file was missing.

This PR will ensure that both the necessary binaries to create the partitions are present.

All the other commands executed in the recovery script seems related to the busybox, if in the future there will be problems with that too, we may consider to extract all the files we need in a folder and chroot it (maybe reusing some functions from init_functions.sh).