Signals the end of an undoable operation. Sends the undo data to the editor undo system and refreshes the graph view with the changes made.
Call this after you trigger a sequence of graph modification methods to finalize recording the operations to the
undo stack. Call Graph.UndoBeginRecordGraph before the sequence to signal the operations to be recorded.
Throws InvalidOperationException if there is no undo operation currently registered to the Graph.