Deprecate legacy libraries

[tobigremmer-dt]

Is your feature request related to a problem? Please describe. As soon as dta has feature parity with existing automation libs, they shall be deprecated.

Missing features (checked when completed):

• [ ] Sending Events

Legacy libraries (checked when deprecated):

• [ ] https://github.com/dynatrace-ace/cloud-automation-tools + https://hub.docker.com/repository/docker/dynatraceace/cloud-automation-tools/general
• [ ] https://github.com/dynatrace-ace/monaco-runner + https://hub.docker.com/repository/docker/dynatraceace/monaco-runner/general
• [ ] https://github.com/dynatrace-ace/ace-cicd-tools + https://hub.docker.com/repository/docker/dynatraceace/ace-cicd-tools/general
• [ ] https://hub.docker.com/repository/docker/dynatraceace/dynatrace-push-event/general (Where is the repo?)
• [ ] https://gitlab.com/dynatrace-ace/dynatrace-gitlab-library
• [ ] https://github.com/dynatrace-ace/dynatrace-jenkins-library
• [ ] https://github.com/dynatrace-ace/ace-jenkins-extensions
• [x] https://github.com/dynatrace-ace/keptn-jenkins-library
• [x] https://gitlab.com/dynatrace-ace/keptn-gitlab-runner
• [x] https://gitlab.com/dynatrace-ace/keptn-gitlab-library

[tobigremmer-dt]

Blocked by #26