chore: [DevOps] Add release environment

[Jonas-Isr]

Context

https://github.com/SAP/ai-sdk-java-backlog/issues/399

This is a left-over of the security hardening topic. The idea is to hide release-critical secrets in a specified environment. Then, any workflow that uses these secrets has to fulfil certain requirements. This is to make sure that no workflow that e.g. runs from a branch can simply use our critical secrets.

I set up an environment release in this repo (see link above) and added the secrets CENTRAL_SONATYPE_SETTINGS_XML, PGP_PASSPHRASE, and PGP_PRIVATE_KEY. I added the protection rule that any workflow that runs and wants to use these secrets needs to be manually approved by a member of our team.

If we want this feature, we afterwards would need to delete the above three secrets from the list of repository secrets.

How it looks

Link to successful dummy run.

Feature scope:

• create environment
• use environment in the workflow

Definition of Done

• Functionality scope stated & covered
• Tests cover the scope above
• Error handling created / updated & covered by the tests above
• Aligned changes with the JavaScript SDK
• Documentation updated
• Release notes updated