Add support to register workflows hosted in private repositories

app/api/dependencies.py

app/api/endpoints/workflow.py

app/api/endpoints/workflow_execution.py

app/api/utils.py

app/crud/crud_workflow.py

app/git_repository/__init__.py

app/git_repository/abstract_repository.py

app/git_repository/github.py

app/git_repository/gitlab.py

app/schemas/workflow.py

app/schemas/workflow_execution.py

app/schemas/workflow_version.py

app/scm/__init__.py

app/scm/scm.py

app/slurm/slurm_rest_client.py

app/tests/api/test_security.py

app/tests/api/test_workflow.py

app/tests/api/test_workflow_execution.py

app/tests/conftest.py

app/tests/mocks/mock_s3_resource.py