Config reference documentation update

[tomas-langer]

Resolves #9036

This PR is a few commits on top of each other.

1. Inroduction of a JSON reader and writer for Metadata (so we can remove dependency on JSON-P/JSON-B from our tools, such as native image extension, config metadata write, and we can replace the text format in service registry with JSON which is better suited for the task)
2. A small fix for builder codegen, so it does not generate service.loader file when empty
3. config-metadata module is re-structured, as it now has multiple child modules; I did not change group id of existing modules for backward compatibility; introduced codegen and docs modules, deprecated processor module
4. Fix to all pom files to use codegen, add plugin dependencies to correctly order Maven reactor, remove processor dependencies from regular Maven dependencies etc.
5. A small fix to logging-jul, to correctly print out how logging is configured even when not running in native image
6. Update to docs pom file, to generate the config reference documentation with profile configdocs
7. Update to the actual .adoc files based on all of the above

This is also a must-have for 4.1.0, as service registry needs to use it

[tomas-langer]

Closed as this is separated into multiple PRs