Implement the Tier-0 Mode

The Tier-0 needs are very special, and we don't have yet a fully
flexible and functional safe mode. This implements an specific
Tier-0 mode which is suitable for Tier-0 custodial, move subscriptions
although it has a few bits hardcoded.
Support T0 insertion through the WMBSHelper

Extend the createSubscription method to encapsulate WMBS and
DBSBuffer injection in the database, move the old createSubscription
to _createSubscriptionsInWMBS
Merge pull request #4634 from dballesteros7/morePhedex

Implement the Tier-0 Mode
Merge pull request #4630 from dballesteros7/t0-1

Support T0 insertion through the WMBSHelper
handle tier0 task archiver config without reqmgr
Merge pull request #4640 from ticoann/t0_modconfig

handle tier0 task archiver config without reqmgr
Adding subsciption info to GET request result

This small modification adds subscription information to the GET REST API call
so information like CustodialSites is listed in the form that is returned from
the workload helper.

Fixes #4588
Merge pull request #4648 from zdenekmaxa/reqmgr-custodialsites-info-added-4588

Adding subsciption info to GET request result