Add Node and NodeManager to SPI
Do not distribute create table plan when in single node mode
TPCH plugin
Convert benchmarks to use CREATE TABLE for data loading
Update to airlift tpch 0.1
Improve encapsulation of native connector interfaces

- Inject NativeMetadata into NativeConnectorFactory, just like DataStreamProvider et al.
- Make NativeSplitManager depend on the connector-specific NativeMetadata instead of global Metadata