Add jsonl support to sstabledump

Add a new option to sstabledump to allow the generation of jsonl format.

The -l option for sstabledump does not produce valid jsonl.

https://jsonlines.org/validator/

Valid jsonl removes whitespace, including newlines, to make the format compact.  

By adding an option to generate valid jsonl, jsonl can be generated that is smaller.

Smaller output is better for execution time, storage, and transport. 

jsonl also allows the splitting of a file for processing at a known good line for processing without parsing the file, as each row is a line.