OAuth2-authorizationCode with PKCE

@nils.brinckmann Please check the flowing urls in the openapi.json→securitySchemes

 "authorizationUrl": "https://login-dev.helmholtz.de/oauth2-as/oauth2-authz",
 "tokenUrl": "https://login-dev.helmholtz.de/oauth2/token",

Edited Jun 07, 2022 by Kotyba Alhaj Taha

Add OAuth2-authorizationCode with PKCE.