Permits async/streaming access to job queues

It's only TapePool in the case of archives, retrieves are filtered on
vid

All new code is now in QueueItor.hpp

For async/streaming access to the contents of archive and retrieve
queues.

Kept the initial algorithm too and created a selection function.

The steps are now base RPMs, EOS and then scripts. This allows faster testing
of new EOS versions.

This multiline string did not go well stored as an extended attribute in EOS.

The situation can happen if the queue was removed but not yet derefernced from the
root entry while another process tries access the queue. This a race condition.
The process trying to access the queue will proceed the with cleanup itself
and retry.

This allows attaching a debugger to the main process.

We should not overwrite the user /etc/sysconfig/cta-taped as it contains site specific configuration

TimeBasedCache::getCachedValue() now returns a stale value if another thread is already determing the new fresh value