Add IncrementalPersistence method to Segment interface & decouple from compaction

[hisundar]

Currently moss store compactions only work for the Basic segment kind since it uses a custom bufferedSectionWriter. Adding an incremental persistence method to the Segment interface will help decouple the compaction logic from the actual implementation of the Segment interface.
This can make moss much more extensible with custom segment types which support unique application needs such as - btrees for faster indexing, compressed segments for smaller file sizes, finite state transducers, bloom filters, etc

[hisundar]

IncrementalPersistence must be a core requirement of any implementation of the Segment interface because it is a fundamental pre-requisite during the merge phase of the Log Structured Merge paradigm. The current bufferedSectionWriter can become the default implementation of this IncrementalPersister interface.