Logging

It would be nice to be able to use the logging macros from the log crate. We can do this by implementing the Log trait.

# // Copyright 2023 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
{{#include examples/src/logger.rs:main}}

• The first unwrap in log will succeed because we initialize LOGGER before calling set_logger. The second will succeed because Uart::write_str always returns Ok.