Ability to set planet request in constant combinators

[Nemoricus]

TL;DR

You should be able to assign "Planet to import from" in the constant combinator interface.

What?

As above.

Why?

Constant combinators can be assigned to use logistics groups that can be shared with landing pads and platforms. However, unlike platforms and landing pads, you cannot set the "Planet to import from" when adjusting the logistics group in the constant combinator interface. While you can work around this by adjusting the groups in the platform or landing pad UI instead, it would be more convenient if you were able to set it in the constant combinator interface as well. This is especially convenient if you're using a constant combinator to control a pad's requests.