fix some style issues

- move and refactor Image.php from Libraries to Entities folder
- update some database field names
/ types
- update composer packages

- update CI process to include quality stage (tests + code review)
- add captainhook to install git pre-commit & pre-push hooks
- remove .devcontainer Dockerfile to use project's docker-compose services: all
services can now be started automatically using vscode
- update docs/setup-development.md

- overwrite myth/auth config with castopod app needs
- create custom views for users authentication
- add admin area bootstrapped by admin controller
- shift podcast and episodes crud to admin area
- reorganize view layouts
- update docs for database migration
- add myth-auth to DEPENDENCIES.md

closes #11