de-duplicate chest code

[a-tour-ist]

@fluxionary already mentioned in #122 that the chest override code is behind mtg. While the specific bug mentioned there got fixed already, other long-fixed bugs from mtg, such as luanti-org/minetest_game#1884 still appear with the pipeworks version.

The approach of this PR consists of 2 parts:

1. The override table for the chests is nearly always the same, mostly only changes in the tiles. So I made a general function to override any given chest to be compatible with pipeworks
2. The splitstacks switch in the formspec:
   • mtg: since mtg opened the chest api (Make default.chest.register_chest() usable for other mods luanti-org/minetest_game#2127), it's no longer needed to duplicate the open chest code, making it much easier to maintain here. (Just dropping Ensure chests close properly luanti-org/minetest_game#2965 as another example that got missed here...)
   • hades: got a large chest update... Now all chests from hades connect to pipeworks. I also updated (copy-pasted) some formspec-creation code from there, so a texture error I get when opening a chest is now fixed.
   • mcl_barrels: that switch did not exist in the previous compat code, adding it would mean a lot of code duplication from there...
     I'd rather opt for a chatcommand/tool to control that value. This would also allow to drop a lot of the code for hades.

I tested everything I can imagine, I hope I missed nothing :-)

[SwissalpS]

ran this on a pandorabox-mods world. I didn't test the duplication part, mainly focused on optics and tube functions on technic chests and machines. No obvious errors found this way.

[BuckarooBanzay]

thanks 👍