Plows and Rockwheels can be converted into JSON effects

[Xion350]

As per @mlangsdorf from the Discord.

So the plow and the rockwheel use copy-pasta of the same code. It could be generalized to take a JSON configuration, something like "transform_tiles": { "base_flag": "DIGGABLE", "new_terrain": "pit_shallow", "failure_damages": true }.

Having this effect in JSON would be useful as you could create vehicle parts that do more than just till earth. The original suggestion was from someone who wanted a vehicle part that could create roads.

[KnightosMaster]

This functionality now exists in the form of transform_terrain, and should probably be closed. @mlangsdorf

[ZhilkinSerg]

It was jsonized in PRs like #31894 and #31913.