Stored `ComponentIDKey` and `OperationIDKey` would still use string
references (char pointers) to data in related IDs, instead of using the
already locally stored std::string name of their matching `ComponentNode`
or `OperationNode` for that.
During undo, to reduce updates and speedup undo steps, a lot of IDs get
'replaced in place', i.e. new data read from the undo memfile is moved
into the existing 'old' ID memory address. And the depsgraph is also
re-used from the old BMain.
Calling `DEG_id_tag_update` and similar on the ID could then cause
depsgraph code to access freed memory from the 'old' data.
Joint effort with @sergey and the rest of the depsgraph team, thanks!
ade103d7b8