inject new squashfs into pak file, add startup script

[zengelan]

Add two features:

1. The unpack-novatek-firmware.pl gets a new -i parameter. With it will inject a new squashfs image into an existing pak firmware update file, so it can be deployed via the web UI, without serial console
2. The repack-reolink-rootfs.sh script now also plant's a startup script that allows to run any commands and scripts from an sd card directory. This allows to make chanhges to the runtime without re-flashing. An example is included where the nginx config is changed to list the directory contents of the sd card an the recordings un html and json

[hn]

Thanks Andreas! It will probably take some days until I review and merge your changes, been busy these days. And I'll likely split the PR into multiple parts (1. Inject pak, 2. Startup script, ...).

[GhostlyCrowd]

@zengelan I am trying to use this, great work by the way but my repacks are not flashing and I believe this is why. also your script just names the repack "1" thats it just 1

File CRC: ef16b88b Calc CRC: a440fb10 Warning: File CRC does NOT match computed CRC value!

That's what the repack tells me when I try to unpack it again which I'm sure is why the flash fails.