fixing rmcd log issue as /var/log/castor/rmcd_legacy.log was a named pipe and nothing was collected in artifacts.

and generating all the required krb5 keytabs

using root instead...

Only eosusers and powerusers can write to it, and powerusers only can drop replicas for all file in this directory.
poweruser1 now drops the disk replica of the file before it is recalled in `client_ar.sh` test script.

adding all the missing bits to allow the simple systemtest to run on the client pod:
- add user `daemon` to sudoer in eos so that we can xrdfs prepare as a `powerusers` user
- add the `powerusers` group mount rule in cta
- add the missing bits in client_test.sh

plus renaming users as stated: users, powerusers, ctaadmins, eosadmins are the one we need in real life.

to allow all users with ctausers as their primary group to mount tapes. the uid-gid mapping is performed by the mgm

the server protocol order precedes over the client order. Therefore if the server is `unix sss krb5`  and th
e client `krb5 unix` the client will authenticate on the mgm using unix, and the created file belongs to `nobody`, but the file transfert can continue with unix and you get a file full of data belonging to nobody. If the client keeps only `krb5` then you get an ampty file belonging to the correct user...

and create all the needed users accounts and groups on the mgm so that we can `xrdcp` files from the `client` pod.

Adding client pod with cta cli and xroot-client using `user1` kerberos ticket for authentication

2 tapeservers are now available: tpsrv01 and tpsrv02.
systest.sh only put tpsrv01 up and perform the basic test on 1 drive only.

This was implemented using the previously created Helpers.

This required to pass an AgentReference through to all garbageCollect() member functions of all objects.
The changed behavior required adaptation of the corresponding unit test (the archive queues now need to
be properly referenced in the root entry).

This field had a meaning when tapepools where stored in the objectstore and the archive queue a static object.
Since the introduction of the catalogue, they are now transient objects and storing their address
is not meaninful anymore.

Factored a first function out of OStoreDB into Herlpers.

Failing to report a migration is non-fatal, as succesfully written files can still be reported afterwards.
synchronousReportEndWithErrors had to be rewritten as instanciating and calling a report would have created a race condition.

The demangling has been ported in other places where RTTI was also used.

Fixed closing file descriptor -1 for lock some (legitimate) error cases of BackendVFS::ScopedLock().

Adapted unit tests to validate this fetching.