Baking simulations for an object with more than one geonodes modifier
creates cache folders for _all_ modifiers, even if some of them do not
actually have simulation zones. The simulations zones also don't need to
be connected to the output to generate cache folders.
This patch restricts cache folder generation to modifiers which actually
have simulation zones and use them.
Extra cache folders were created because executed modifiers were only
checking if a simulation state exists and not whether it contains actual
zone data (`sim_state->zone_states_.is_empty()`). The modifiers are
always executed if the object is evaluated by the depsgraph, which
happens if _any_ of the modifiers is time-dependent. Time dependency in
turn is enabled if a simulation zone exists in the tree, regardless of
whether it is used.
Checking for zone states in the cache output during baking lets us
decide if a cache folder is needed.
Pull Request: https://projects.blender.org/blender/blender/pulls/108278
Lukas Tönne
292baa2a1d