OAuth2 enhancements
- Added the security extension Proof Key for Code exchange (PKCE) to the OAuth 2, supporting PKCE (plain) and PKCE (S256)
- The OAuth2 discovery process will get information about the supported PKCE of the OAuth2 provider. The discovered data can be taken directly as preset for the OAuth 2 process.
- Added the possibility to add custom parameter to the authorization process URI
- Added some more OAuth2 provider templates to the presettings option