[ATR-24327][ATR-24409] Add UseDirectMenuAccess flag to the TDT and use it in RAWtoALL

A bit more invasive than planned, but such are things...

1. As laid out on ATR-24327, I give the TDT the ability to fetch the four JSONs itself when m_useDirectMenuAccess=True.

From here it's similar to e.g. the xAODConfigSvc, we use the JSON to populate a bunch of legacy config objects (here owned by the per-slot CacheGlobalMemory object), and from these do the TDT's internal configuration in the way it expects.

2. We don't schedule the xAODConfigSvc in RAWtoALL (specifically we refuse to return this when InputContainsConfigMetadata == False)

3. The Trigger/TriggerCommon/TriggerJobOpts/python/TriggerConfigGetter.py is further tided up following the work of @fwinkl, we get it even more streamlined here.

4. Event/xAOD/xAODTriggerCnv/src/TrigDecisionCnvTool.cxx then has a problem as it was also using the xAODConfigSvc in RAWtoALL of R1, R2 data

We remove the xAODConfigSvc, it needs access to the list of chains - but it can also get this through the TDT's expert methods.

The TDT's expert methods are expanded to add a function for this (up to now it would only look up specific chains)

The Event/xAOD/xAODTriggerCnv/src/TrigDecisionCnvTool.cxx now needs to be explicitly linked against Trigger/TrigAnalysis/TrigDecisionTool/Root/TrigDecisionTool.cxx - we can no longer use the ITrigDecisionCnvTool interface as this is too basic (it has isPassed and that's about all)