Forest trash updates, make field stone a bit more common and useful

[NetSysFire]

Summary

Content "Make field stone a bit more common, which can now also be turned into rocks. Plus general small forest trash updates."

Purpose of change

See below.

Describe the solution

Field stone:

1. Field stone can now be found while digging. In real life it is mainly exposed through frost churning, pushing the rocks upwards. Logically, you can find some when you dig.
2. Field stone can also be found lying around in forests and thus can be foraged.
3. Field stone (1L per item) can now be crafted into 3 rocks (750 ml) with 9 (225 ml) pebbles as a byproduct. This is an intentionally slightly lossy process as bashing rocks into pieces will always yield small splinters that get lost. Bashing rocks into pieces is not knapping, so it does not train that proficiency.

Other forest trash updates:

1. Buff twig spawns. I went hiking and there are a looooot of twigs.
2. 1-3 rocks can be found if the RNG decrees it shall be rocks.
3. Moar splinters, too.
4. Some pebbles can randomly be found, too.
5. Very rarely, you may find a log. Yes, many logs in forests may be rotten, this is why this is a miniscule chance.
6. Sync forest trash changes with innawoods, including some "backporting". CC @Light-Wave for this.

Describe alternatives you've considered

@Maleclypse unrelated and out of scope, but do you think the kiln, rock forge and related constructions should use field stones, too?

Testing

Applied changes locally. New recipe crafts as intended. Digging result yields field stone.

Additional context

[Maleclypse]

I wish we could do percentage based crafting where you set a volume then a list of objects and a percentage for each object so that you could set a max percentage of the volume that could be occupied by that object id. Then I'd be ok with it though I suppose we could manually do that by creating a line that has rocks and fieldstones as options and then a line that only has rocks as an option. The reason I'd want that is that the fieldstone I'm familiar with could be useful as a base for those furnitures but you'd want smaller rounder rocks for most of the walls to better fill in cracks and prevent heat loss through the gaps.