DRILL-7314: Use TupleMetadata instead of concrete implementation1. Add ser / de implementation for TupleMetadata interface based on types.2. Replace TupleSchema usage where possible.3. Move patcher classes into commons.4. Upgrade some dependencies and general refactoring.
DRILL-6676: Add Union, List and Repeated List types to Result Set LoaderAdds required functionalty to the list and repeated list vectors.Row set accessor changesAdds a "variant" type to model both unions and (non-repeated) lists (which can act as a repeated union, among other things.)Adds union, list and repeated list support to the result set loader and associated classes.Copied much of the general documentation from my private Wiki into mark-down files.closes #1429