Summary:
Implement a parsing tool io_tracer_parser that takes IO trace file (binary file) with command line argument --io_trace_file and output file with --output_file and dumps the IO trace records in outputfile in human readable form.

Also added unit test cases that generates IO trace records and calls io_tracer_parse to parse those records.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7333

Test Plan:
make check -j64,
 Add unit test cases.

Reviewed By: anand1976

Differential Revision: D23772360

Pulled By: akankshamahajan15

fbshipit-source-id: 9c20519c189362e6663352d08863326f3e496271