Implement role-based access control and permission system

[eliaspr]

• Implement new DB structure & role assignment checks (Database & backend changes for new RBAC system #37 )
• Add endpoints for managing role assignments (Add endpoints for getting and modifying role assignments #40 )
• Add UI for managing role assignments
  • View / Delete role assignments (Add UI for viewing & deleting RBAC role assignments #42 )
  • Add role assignments (Implement UI for adding RBAC role assignments #50 )
  • Add better/specific handling for 403 response
• Disallow actions in the UI which would fail due to 403 (Implement client-side authorization checks #73 )
• Add 'PrincipalId' property for users and api keys (Add 'PrincipalId' property for api key and user entities #46 )
• API keys can be used for all endpoints
• Add role that only allows reporting match outcomes (Add new 'Reporter' role and corresponding action #58 )
• Remove role assignment description (Drop 'Description' property from role assignment entity #52 )
• Order role assignment groups by pre-specified order (Ensure consistent ordering of assignment groups #53 )
• Resolve display name of principal in role assignment list (Resolve names of role assignment principals #54 )
• Fix TODO comment in DeletionHelper.cs (Fix delete user UI inconsistency and display missing principals #61 )
• Owner role is required for deletion of organization (Require 'Owner' role for deleting an organization #62 )