v8.0.23

[rel-v8r0]

FIX: (#7061) Close DISET selector when we no longer need it

*WorkloadManagent

NEW: (#7049) New TornadoSandboxStoreHandler implementation

*Core

NEW: (#7049) TornadoClient - added sendFile() method

*Resources

NEW: (#6970) add a test for the PoolCE to highlight the fact that submission failures cannot be handled by the caller with the return value

*WorkloadManagement

FIX: (#6970) management of the job status in JobAgent
NEW: (#6970) add a test for the JobAgent to make sure the status of the submissions are correctly handled

*docs

NEW: (#6970) documentation about ComputingElement

*WorkloadManagementSystem

NEW: (#6914) new script dirac-admin-add-pilot