Deployment to Maven Central SNAPSHOT

[wadoon]

Related Issue

This pull requests allows the nightly_deployer to deploy Maven CENTRAL Snapshot.

Currently, my tokens are added as secrets. Job step was tested here: https://github.com/KeYProject/key/actions/workflows/publish_test.yml

In the current version, we deploy to [https://git.key-project.org].

Intended Change

Plan

• Implement feature 1
• Implement feature 2
• Code cleanup
• Document the changes

Type of pull request

• Bug fix (non-breaking change which fixes an issue)
• Refactoring (behaviour should not change or only minimally change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• There are changes to the (Java) code
• There are changes to the taclet rule base
• There are changes to the deployment/CI infrastructure (gradle, github, ...)
• Other:

Ensuring quality

• I made sure that introduced/changed code is well documented (javadoc and inline comments).
• I made sure that new/changed end-user features are well documented (https://github.com/KeYProject/key-docs).
• I added new test case(s) for new functionality.
• I have tested the feature as follows: ...
• I have checked that runtime performance has not deteriorated.
• For new Gradle modules: I added the Gradle module to the test matrix in
  .github/workflows/tests.yml

Additional information and contact(s)

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.