Add configuration on CTA SSI frontend to block user and/or repack operations

Situation

We plan to split the objectstore backend between repack and user instances.

This will leave us with two different groups of CTA frontends, each one communicating with a different objectstore backend:

• ctaproductionfrontend(ops): User operations
• ctaproductionrepackfrontend(ops): Repack operations

To make this work properly, we need to be able to configure each frontend to block operations of the wrong type.

Task

Add two new configurations to the CTA frontend:

• cta.schedulerdb.enable_repack_requests on|off
• cta.schedulerdb.enable_user_requests on|off

Each one of them, if off should cause any requests of that type to be refused.

By default both should be on.

Link to config file example:

• https://gitlab.cern.ch/cta/CTA/-/blob/main/xroot_plugins/cta-frontend-xrootd.conf.example