Add more control over in-toto-run command standard streams

[lukpueh]

Description of issue or feature request:

Current behavior:
in-toto currently either completely ignores standard streams (default) or duplicates them, i.e. prints them to the console and records them in link metadata (on --record-streams/record_streams=True).

Expected behavior:

in in-toto-run

• Per default print standard streams to console but don't record them in link metadata
• Use --quiet to disable printing streams to console
• Use --record-streams to enable recording streams in link metadata

in runlib.in_toto_run

• Per default don't print standard streams to console and don't record them in link metadata
• Add quiet keyword argument (default True) to enable (False) printing streams to console
• Use record_streams keyword (default False) to enable (True) recording streams in link metadata

Implementation hint:

Use securesystemslib.process.run_duplicate_streams if not quiet and record_streams, and securesystemslib.process.run in all other cases.