Contribute to add Neptune 3 Pro support

[zetiti10]

Hello!
I have an Elegoo Neptune 3 Pro which I modified to make it run on Klipper. Basically, I added a Raspberry Py inside the base. To keep the stock display working, I initially found the KlipperLCD project (https://github.com/joakimtoe/KlipperLCD) which does the job. However, it uses the Neptune 3 stock firmware. I recently discovered this project and I find it better as it uses the Neptune 4 display firmware. For example, I can't turn off the host properly before shutting down the printer with KlipperLCD.
I was able to make the project work on my installation by changing some names in the files (such as changing the user in scripts, which is hard-coded to mks). Main functions are working properly, but it's not all perfect because the project is made for Neptune 4 printers.
I explored source files of the project to understand its structure. I discovered that there is a beginning of adaptation for Neptune 3 printers, but it isn't finished.
I could modify the Neptune 4 classes to fit my installation, but it would be messy and other people couldn't benefit from my work. So, I want to try finishing the Neptune 3 implementation to make the project fully works with this printer generation.
I believe I understood pretty well the global organization of the program. I'm still a young python programmer and I never contributed to existing open source projects, but there has to be a beginning for everything!
What do you think about all that ?
I can provide more details.