Split up circleci config

[ztefanie]

For better readability circleci config should be split up.

• Create the subfolder src/commands src/jobs and src/workflows inside .circleci
• put every command, job and workflow in a separate file
• create autogenerated header file
• add commands to merge file to a config file
• create a check if config file is up to date
• add the check to ci if config file is up to date