Add jooby-rainbowgum logging module

[agentgt]

@jknack

I have newer logging framework that has some advantages over log4j2/logback:
https://github.com/jstachio/rainbowgum

I can add the module to jooby as a PR or can manage it in the Rainbow Gum project itself if you prefer (hence the bug filing).

The nice thing about the Rainbow Gum module is that will use the normal Jooby configuration (typesafe config) similar to how Spring Boot can configure logging with its configuration framework.

[agentgt]

Oh I probably do need to keep it separated for now because it targets JDK 21.