Ensure DB returns datetime with timezone set and fix more issues with timezones

api/src/api/routes/site.py

...n_py/src/videoag_common/api_object/fields/basic_fields.py

common_py/src/videoag_common/database/__init__.py

common_py/src/videoag_common/database/drift_detector.py

common_py/src/videoag_common/database/utc_timestamp.py

common_py/src/videoag_common/miscellaneous/util.py

common_py/src/videoag_common/objects/changelog.py

common_py/src/videoag_common/objects/course.py

common_py/src/videoag_common/objects/job.py

common_py/src/videoag_common/objects/medium.py

common_py/src/videoag_common/objects/site.py

common_py/src/videoag_common/objects/stats.py

common_py/src/videoag_common/objects/user.py

job_controller/jobs/source_file_sorter/job.py

...oller/src/job_controller/executor_api/job_executor_api.py

...troller/src/job_controller/executor_api/kubernetes_api.py