Renamed CTA/tapeserver/castor to CTA/tapeserver/castor_checkout in preparation for the moving the sub-directory CTA/tapeserver/castor/castor up the directory tree

errors for a non-crashing session can also be recorded as a failures in the
tape log.

CASTOR-4751: tapeserverd does not report drive as empty and does not finish client session if user does not have migration access-rights

The error situation was already generating an exception, which went all the way to the caller
of the data transfer session. It is now intercepted and the client is notified synchronously.
The session now ends successfully (the drive was not touched).

CASTOR-4765: The heartbeat messages of the data-transfer session of tapeserverd should include valid drive unit-names

Partial implementation of the ticket:
- The reporting to client and session exit part has been dismantled.
- The template based implementation of the watchdog has been changed to a more classing inheritance schema.
- The reporting to mother process of the moved blocks has been re-enabled.

The C++ namespace castor::tape::tapeserver::drive now matches its
directory structure.

Created a unit test for validating the propagation of end of tape if the error happens during a flush.
Updated the FakeDrive to generate the error.
Added support for the propagation of ENOSPC error when it happens durring a flush.
Added support for end of session status recording by the FakeClient and checks in the related unit tests.

Reviewed and fixed the error handling for migrations.
A deadlock was created by the competing usage of a stop variable an normal information flow
through the threads. The global variable's usage has been reduced and clarified:
it is set by the tape thread to indicated an error reached it. From that point
on, the remaining disk threads can stop what they are doing (and not before as failing
to read a file should not block the completion of previous ones).
The file errors are now transmitted to the client before end of session, and in case of flush.
The unit tests have been updated accordingly.
Report messages have been improved.

This implied adding file block ID tracking in TapeFile::WriteFile

TaskWatchDog is now template, can detect when the drive is stuck and ask the right report packer to report that file as wrong, close the session and kill the whole process

and DiskReadThreadPool

Compute it on DiskWriteTask and report it to the Client. Tests and interfaces have changed consequently

DiskReadTask -> DiskReadTaskInterface, DiskReadFileTask -> DiskReadTask, same thing for the write side. Changed the includes files accordingly

Moved all files related to Client to client/, changed the namespace and fixed the files consequently (header,usings,...)

log, client interface and m_listReports are now inherited from the base class

We are now using the matching files and classes frpm castor/tape/threading