Design of execution manager

[prasadtalasila]

The execution manager is responsible for executing digital twins as jobs on cloud infrastructure. To kickstart the development, the execution manager will be initially made responsible for executing digital twins as gitlab CI jobs. There is already an initial structure in place for executing digital twins as gitlab CI jobs but this is based on curl requests. Such API calls need to be integrated into the execution manager.

The conventions used for integration of gitlab CI into DTaaS are implemented in this gitlab repository. There are two gitlab client libraries, namely gitbeaker and python-gitlab. The frontend uses gitbeaker but we will use python-gitlab for execution manager.