Fix T98157: improve animation fps with better check in depsgraph

Previously, the depsgraph assumed that every node tree might contain
a reference to a video. This resulted noticeable overhead when there
was no video.

Checking whether a node tree contained a video was relatively expensive
to do in the depsgraph. It is cheaper now due to the structure of the new
node tree updater.

This also adds an additional run-time field to `bNodeTree` (there are
quite a few already). We should move those to a separate run-time
struct, but not as part of a bug fix.

Differential Revision: https://developer.blender.org/D14957

source/blender/blenkernel/intern/node.cc

@@ -670,6 +670,7 @@ void ntreeBlendReadData(BlendDataReader *reader, bNodeTree *ntree)
 
   ntree->progress = nullptr;
   ntree->execdata = nullptr;
+  ntree->runtime_flag = 0;
 
   ntree->field_inferencing_interface = nullptr;
   BKE_ntree_update_tag_missing_runtime_data(ntree);