Performant stdout and stderr logging

Improvements:

• Separate handling for stderr pipe.
• Log multiple lines at once i.e. performant logging.

Initial Stable Release

XCTool functionalities:

• Execute performance UI/Unit tests.
• Re-run failures due to a flaky environment.
• Parse test summaries from result-bundle(s) produced in a test-run.

Performance testing CI pipeline(s) can use/extend XCTool functionalities in their development workflow.