root_system feature config's codec uses a wrong field

The codec of RootSystemFeatureConfig class uses the requiredVerticalSpaceForTree field twice, one for required_vertical_space_for_tree, the other for allowed_vertical_water_for_tree.

It makes the allowedVerticalWaterForTree field unused, and prevents the feature to work as expected.

Affected parts of the codec:

.fieldOf("required_vertical_space_for_tree").forGetter(arg -> arg.requiredVerticalSpaceForTree)

.fieldOf("allowed_vertical_water_for_tree").forGetter(arg -> arg.requiredVerticalSpaceForTree)