Logging boltons

[adriangb]

There's a couple pure-python logging tools/utils that I find myself re-implementing often. I wonder if they could be added here:

• A bind function that works like Loguru's bind() but w/ any logger, and is thread & coroutine safe.
• A testing tool like structlog.testing (or unittest.assertLogs in it's simplest form) that allows you to capture not only log records but also formatted output.
• A tool like contextlib.redirect_stdout but that doesn't do it by monkey patching the sys module (that's how contextlib.redirect_stdout works) an instead operates at the os file descriptor level (os.dup/os.dup2).