Control where TB writes output (stdout, file, or both)

[vloncar]

Description

Testbench currently writes to file and to stdout. stdout may have limits in some environments (like the CI), obscuring important output. This PR makes it configurable via TBOutputStream of the WriterConfig section of the config.

Type of change

• New feature (non-breaking change which adds functionality)

Tests

Added test test_tb_output_stream to test_writer_config.py but skipped for now because it requires HLS tooling.

Checklist

• I have read the guidelines for contributing.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have installed and run pre-commit on the files I edited or added.
• I have added tests that prove my fix is effective or that my feature works.