List wrapper SCOs have inefficient initialise method when updating (setXXXField). Create efficient logic for working out changed elements

[andyjefferson]

The structure for changing this is now in place in DN 4.1 and has been done for Sets, Maps. So wrappers for Lists can be modified from 4.1 onwards without needing other plugins changing.

See https://github.com/datanucleus/datanucleus-core/blob/master/src/main/java/org/datanucleus/store/types/wrappers/backed/ArrayList.java#L133 which currently does a clear() of the old list and addAll() of the new list.