Using the Documentation Annotations for Server

[janheise]

Description

This PR moves the Documentation Annotations used in DataNode to https://github.com/Graylog2/JadConfig and also implements these in the server package.

This is a first draft!

/nocl - internal refactoring, no user facing change

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have requested a documentation update.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.