cli: Add `swh scanner login` command
The login command helps user to authenticate through OIDC and possibly save OIDC configuration to global yml configuration file
- Make use of swh auth for OIDC authentication
- Ensure correct default 'keycloak' configuration
- Load configuration file via arg, env, or default global path
- Add a 'login' command to scanner cli that invoke swh auth config
This one supersed !72 (closed)
It depends on swh-auth swh-auth!55 (merged) to be merged and released