Improved poe_set_ip.py script usage and reduced chance of errors.

[ahrastnik]

Improves the poe_set_ip.py example.

• Added input validation
• Added command for getting the currently set IP in order to verify it
• Made it so the command can be run in one step, so it's easier to set multiple devices

[themarpe]

@Erol444 please review & merge if okay

[Erol444]

@ahrastnik Could we also update the docs for this example?
https://github.com/luxonis/depthai-python/blob/main/docs/source/samples/bootloader/poe_set_ip.rst
Just on how to use the script/args
Otherwise LGTM, works as expected

[ahrastnik]

@Erol444 done. I've also noticed there's a C++ version of the script. It would be best to get someone to update that too for the sake for completeness.