[SDK] DefaultLogHandler to print errors to std::cerr, add LogLevel::None

[marcalff]

Fixes #2611

Changes

Please provide a brief description of the changes here.

• Fixed the default log handler to print errors and warnings in std::cerr instead of std::cout.
• Implemented a new LogLevel::None

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed (N/A)