A similar question was asked on our official forums. https://forum.smartlydressedgames.com/t/map-editor-update-teaser-i-have-no-words/18895/51?u=moltonmontro
In short, the new equivalent is the "Auto" brush tool. Baking materials across the entire map in one action swoop is no longer available. Foliage can still be baked in a similar-ish manner.