Updated to version 1.15.0

[michaelselby-signaloid]

This pull request introduces a new cross-check to ensure that every Ux string recorded in a tracing database is also printed to stdout, and refactors the Ux string comparison logic to operate directly on stdout output rather than on tracing databases. This change improves the reliability of benchmarking, especially when comparing optimized (-O2) and unoptimized (-O0) builds, and ensures that the verification process is not undermined by build configuration constraints. The update also adds comprehensive tests for the new check and clarifies documentation to reflect the new approach.

New Ux string cross-check and testing:

• Added check_traced_values_printed.py, a module that verifies all Ux strings recorded during a tracing run are also present in the run's stdout, with detailed reporting and robust error handling.
• Added check_traced_values_printed_test.py, providing unit tests for the new cross-check logic to ensure correctness and reliability.

Refactoring and documentation updates:

• Refactored compare_tracing_ux_strings.py to compare Ux strings printed to stdout instead of reading from tracing databases, updating logic, reporting, and documentation to match the new approach.
• Updated the README.md to clarify that the -O2 verification now compares Ux strings from stdout, not from a tracing database, and explains the rationale and implications for verification.