Include src code todos into GitLab

TODO

Summary

The current code base includes TODOs from Phabricator (or also unspecified ones). The goal is to have them in GitLab to have a better overview.

This is an example (in python):

# \todo(#123): Refactor this function to improve performance
def calculate_data():
    pass

The \todo syntax ensures that you also have it in your doxygen documentation.

Subtasks

• Go through your current TODOs
• Create a GitLab TODO based on the template
• Change the old TODO to the new style

Acceptance Criteria

• No todos without a GitLab issue number should exist in both tools and libraries