WIP convert test stores to dstore
WIP Selection update and test fixes
Update inline TODOs and fix handling of _getFirstRowSibling
Convert remaining List `store` refs to `collection`
Make more test data fixes for dstore
Remove OnDemand-removeRow tests

OnDemand-removeRow tests dgrid functionality made unnecessary by dstore.
Fix error message to refer to 'collection' rather than 'store'
Fix _trackError to encapsulate sync/async cases