LANA support for message severity

[thedoc31]

As we mature with our implementation of LANA, it's become clear that the existing errorType = implicit or explicit does not cover the full realm of possibilities teams may want to send in, monitor, and alert upon.

To that end, I've added support for a severity parameter in the LANA AIO app (not yet promoted to production) with values [1]. The errorType variable remains, and a user can still specify implicit or explicit as desired. Nothing changes there.

A message can include only one severity, and messages by default will be classified as info if not otherwise specified. If someone enables debug mode and does not otherwise specify a type, it will instead default the severity to debug.

Are there any other logging levels missing or implementation concerns? I'll need to update the Milo lana logger to support it, then will submit a PR.

[1]

d / debug
i / info
w / warning
e / error