Add `remove_items2` and `can_remove2` as a clean replacements

Reason: tube.remove_items(pos, node, stack, dir, count, listname, i) and tube.can_remove(pos, node, stack, dir, listname, i) are currently flawed as they ..

1. .. have arguments that are ordered differently to the inventory callback API provided by Luanti.
2. .. have a superfluous node arg
3. .. do not provide player information --> useful in can_remove

Request:

• Implement and document tube.remove_items2(pos, listname, index, stack, player, dir) (where dir is additional)
• tube.can_remove2 likewise.
• The returned stack should be removed by pipeworks and not the callback. Compare with on_metadata_inventory_take, where this is already done well.

I also thought of extending fakeplayer with a field to indicate the pipeworks origin, such that allow_metadata_inventory_take could be used, however, then there's no direction information, which might be needed in some cases.

Start by locating the existing tube.remove_items and tube.can_remove callbacks, then compare their argument handling with on_metadata_inventory_take. Implement and document the remove_items2 and can_remove2 interfaces described in the issue, including player and direction information. Done means the returned stack is removed by pipeworks rather than by the callback, with the documented signatures available to tube users.