Implement OpenID Connect and SAML 2.0

[SamuelWei]

Fixes #300

Fixes #20

Type (Highlight the corresponding type)

• Bugfix
• Feature
• Documentation
• Refactoring (e.g. Style updates, Test implementation, etc.)
• Other (please describe):

Checklist

• [ ] Code updated to current masters head
• [ ] Passes CI checks
• [ ] Is a part of an issue
• [ ] Tests added for the bugfix or newly implemented feature, describe below why if not
• [ ] Changelog is updated
• [ ] Documentation of code and features exists

Changes

• Refactor LDAP Auth
• Add OpenID Connect
• Add SAML 2.0