Added repack_systemtest.sh that allows to execute a repack on a specified VID with only cta-admin and eos commands

Created a repack_systemtest_wrapper.sh script to allow to execute the repack_systemtest.sh in the CI
Adapted the simple_repack.sh script so that it uses the repack_systemtest.sh script

Wrapped the content of MaintenanceHandler::runChild() into a new method MaintenanceHandler::exceptionThrowingRunChild()

This has been done in order to avoid the MaintenanceHandler to leak exceptions

The garbage collector now sets a flag on the agent object indicating garbage collection.
The process will immediately exit when detecting garbage collection.

This triggered the killing of the maintenance process by a sibling which had an unhandled exception and
hence called the destructor of the MaintenanceHandler. Usual use case sees an exit instead with no
full stack unwinding.

The status of the repack request is updated throughout all its lifecycle (Pending, ToExpand, Starting, Running, Complete or failed)

Flushing stdout and sending ERROR messages to stdout as redirection would be applied to stdbuff command

Fixed.

Moreover, the PL/SQL code for the CTA catalogue is temporarily
moved out of the catalogue folder as it requires some schema
changes that are still work in progress in a dev branch. Until
then, all migration code is evolved in the migration/ folder.

Moved disk-operations-related code into the new "disk" directory

Removed helgrind error by removing a linkage in the tapeserver/castor/tape/tapeserver/file/CMakeLists.txt file

Refactored the async deletion of repack subrequests files via XRootD (used the xroot's async deletion)
Deleted the folder containing the repack subrequests files (Local file + XRootD)

The folder containing the files need now to be removed

Added the creation of the directory corresponding to the vid of the tape to repack (xroot + local file system)

References:
https://gitlab.cern.ch/cta/CTA/issues/479 (on the CTA side)
Jira: CASTOR-5526: support the migration to CTA (on the CASTOR side)

The latter won't be updated further, all required code will
be committed here and gitlab tickets will be updated accordingly.

Fixes race condition: for text stream responses, guarantees that
header is printed before the stream data.