JWT Compliance testbed

• added prague dCache 7.2.x and XRootD 5.4.x version
  • WLCG AuthN/Z documentation
  • dCache documentation issue#6607
  • OSG XRootD documentation
• plan to improve existing documentation for WLCG JWT tokens
  • allow more sites to start with WLCG JWT tokens
• describe minimal versions usable for HTTP / xroot transfers with tokens
  • XRootD - correct storage.create:/ support should come in 5.5
  • dCache
    • 7.2 provides separate OIDC and SCITOKEN plugin
      • WLCG JWT tokens supported by SCITOKEN plugin
      • sufficient support for our tokens
    • 8.2 provides more generic OIDC that can be used instead of SCITOKEN plugin
      • SCITOKEN plugin will be still available / supported for next ~ 2-3 years
      • very small changes required while moving from SCITOKEN plugin to OIDC
    • 8.2 xroot comes with Multiple authentication protocol chaining
      • looks like a useful feature for X.509 to tokens transition with xroot protocol
• we should start to advertise well in advance storage updates required for tokens
  • during data taking preferred windows for updates are winter shutdowns
  • dCache - sites could still use 7.2 with just configuration update
    • we should provide carrot
      • 8.2 can use improved OIDC plugin => different future proof configuration
      • 8.2 provides better support for xroot with tokens
    • we have to come with recommended OIDC identity mapping
      • compatible with concurrent X.509 usage(?)