Geometry Nodes: Make simulation caching optional

For realtime use cases, storing the geometry's state in memory at every
frame can be prohibitively expensive. This commit adds an option to
disable the caching, stored per object and accessible in the baking
panel.

TODO:
- [ ] Seeking backwards in the timeline causes output node to emit default values

@@ -146,6 +147,12 @@ struct StatesAroundFrame {
   const ModifierSimulationStateAtFrame *next = nullptr;
 };
 
+struct MutableStatesAroundFrame {

@@ -1267,2 +1267,4 @@
   const Vector<BMeshToMeshLayerInfo> info = bm_to_mesh_copy_info_calc(bm.vdata, mesh.vdata);
   MutableSpan<float3> dst_vert_positions = mesh.vert_positions_for_write();
+
+  std::atomic<bool> any_loose_vert = false;

@@ -1207,9 +1207,12 @@ static void prepare_simulation_states_for_evaluation(const NodesModifierData &nm
     return;
   }
 
+  exec_data.simulation_cache = nmd_orig.simulation_cache;

@@ -81,0 +99,4 @@
+        const float scene_ctime = BKE_scene_ctime_get(scene);
+
+        std::cout << "Removing state at " << scene_ctime << "\n";
+        modifier_data.prev_simulation_state->remove_zone_state(zone_id);

@@ -1352,2 +1352,4 @@
   }
 
+  if (!(ctx->object->flag & OB_FLAG_USE_SIMULATION_CACHE)) {
+    nmd_orig->simulation_cache->clear_prev_states();