RocksHarnessHelper for RocksSortedDataImpl

* Hook up RocksSortedDataImpl to sorted data interface tester
* Bunch of fixes in RocksSortedDataImpl. I'm not sure of some of the semantics since there is no interface documentation, but this seems to pass the unit tests
* Fix some compile issues due to upstream changes
* Fix RocksRecoveryUnit according to documentation in RecoveryUnit
* Add .clang-format file to rocks root dir, which will help us style our code
* Fix rocks_sorted_data_impl_test