- currently when we have multiple child elements in a sequence with the same name, daffodil allows it, while choice branches return a UPA error and unordered sequences return an SDE. We want to generate a warning when this happens in an ordered sequence so we refactor code to warn if the local names are the same. This has the effect of warning whether namespaces are supported or unsupported
- we group using elementChildren instead of groupMembers since we want to consider all children since regardless of the model groups, their immediate children end up as siblings in the infoset and can cause potential ambiguities for some infoset types
- add test to check we get UPA error with choices
- add tests to exercise new warning (same/different namespaces, but same local name)

DAFFODIL-2736

- remove groupChildrenBy

DAFFODIL-2736