Toggleable landing pad logistics

[dmikalova]

Currently with landing pads if they have an item and there is a request for that item then bots will come and take that item. It would be nice if there was an option to toggle the logistics availability of landing pads so I could not have robots take things from landing pads.

Two example situations:
- I have all my Nauvis science come in through a landing pad. It then gets output onto a belt which uses a buffer chest buffer - the inserters fill chests to 8k of each science, and the chest requests the full 9.6k so if I have any science end up astray it gets cleaned up. Now when the buffer is not full and science lands at a cargo pad, the bots will pull it rather than letting the belts handle it.

- I have a mod enabled to allow multiple landing pads. On Fulgora I import ice from space. I also have all of my outposts configured to pull everything in the logistics network and have a train come pick it up to take it to the main base - this keeps my outposts tidy of any mess from setting it up. However I then have to filter out the ice from the tidying system.

Admittedly these are both niche examples, but I also looked at the landing pad prototype and it doesn't seem like there's a way for mods to control this either. Would be nice to have, whether in the prototype or game itself.