Introduce deprecation & incubation

[sebastianpfischer]

In order to release 1.0.0 we want to ensure our deprecation and incubation process is in place

Capabilities

• extend the doc to explain the process (could be done based on https://www.sebastianpfischer.com/index.php/2023/02/21/how-to-deal-with-breaking-changes-python/)
  • should contain the process to deprecate APIs and features
  • should contain the process to incubate new APIs and features
  • should describe how the documented API looks like
• automate some tests & validation
  • we should have a directive (something like :deprecation: and/or :incubation:)
  • we should have an automated check if thinks marked as deprecated are really shown as such, etc...
  • the changelog should be adapted to reflect features in incubation and the one that are being deprecated.

Acceptance Criteria AC1: Documentation or the process AC2: Implementation of the tooling to validate them AC3: One-run

[sebastianpfischer]

@Pog3k, I will need your implementation power here ^^