Add waterstrainer:fertilizer to tree_extractor as a known fertilizer

[kiskoza]

I created an automated tree farm and I used waterstrainer's worm bin to filter out apples to make it easier to process the logs. Then later I created an arboreal extractor to produce resin and I thought that I can push my fertilizers from the worm bin to the extractor to make it faster, but it wasn't possible. As the text says something like "Use fertilizers to boost production", I added waterstrainer's fertilizer as a viable option with the same boost parameters as bone meal has.