[toolviews] refactor in preparation for new features
- move code into src folder
- add pre-commit and make improvements to tox
- move dbname to default_config.yaml
- move tests to tests folder
- add Procfile
- move codes to be reused later into utils
- any other minor changes not mentioned here
Bug: T317953
Signed-off-by: raymond-ndibe rndibe@wikimedia.org