Generate RLE logo with postmarketos-mkinitfs

The sony-taoshan's bootloader displays a logo that is stored as /logo.rle in the initramfs. This probably works with more devices. Right now, we have the following logo stored in the pmaport, already encoded in the RLE format and in the device's resolution:

But it would be nice if we could generate such a logo file dynamically as @drebrez pointed out, with a deviceinfo variable:

So maybe the easiest solution is to add a deviceinfo variable (deviceinfo_generate_rle_logo?) and in the mkinitfs.sh script generate this additional file

@Halamix2 noted that it would be good to not have exactly the same image displayed as the loading screen in the initramfs, so it's easier to know where boot hangs.

The original discussion with links to programs that generate such a file is here: !71 (diffs, comment 118143485)