Enable different login flows

[tamslo]

See the login implementation in the study version (Sinai VPN and login required) and in the Health-X demo branch

• Extend lab class with login type (see HealthX branch)
• Add oauth-authorization-code-flow (current implementation), app-share (HealthX implementation), and oauth-resource-owner-password-flow (current Sinai implementation)
• Render and conduct login dependent on login type
• Add the option of different endpoints for annotations depending on login (with fallback if not specified)
• Potentially add the possibility to show logos of logins
• Improve loading messages (could also make this new ticket referencing this one and Move security features from study version to main version #700): logging in, checking for updates, loading data & success screen only if genetic data loaded