Refactored test fixtures. Added search tests.

.vscode/launch.json

docs/reference.rst

docs/test_fixtures.png

nomad/coe_repo/calc.py

nomad/coe_repo/user.py

nomad/datamodel.py

nomad/infrastructure.py

nomad/migration.py

nomad/processing/data.py

nomad/search.py

tests/__init__.py

tests/bravado_flask.py

tests/conftest.py

tests/processing/test_base.py

tests/processing/test_data.py

tests/test_api.py

tests/test_client.py

tests/test_coe_repo.py

tests/test_files.py

tests/test_migration.py