WIP: Add macros for using the OTP 21.0+ logger

[codeadict]

This is part of an evil plan to transition from lager to the OTP 21.0 logger as the VerneMQ logging framework.

But why, what does logger can offer?

• Structured logs including JSON logs (container and DevOps people love these)
• overload protection mechanisms
• default logs metadata
• one less dependency to worry about, and in the future lager plans to default to the logger
• plugins don't have to include lager, when I was developing plugins had problems a few times from using a different lager version than VerneMQ had

More info at https://ferd.ca/erlang-otp-21-s-new-logger.html

Upcoming series of PRs coming to other Verne Repos and documentation.

[ioolkos]

great plan! :)