Pilot.json : add a new format

[fstagni]

This issue is a follow-up of discussions happening in the thread started at #6208 (comment)

PilotCStoJSONSynchronizer creates at the moment of writing a custom pilot.json file, composed of 2 parts: the first contains pilot-related information taken from the Operations/<>/Pilot CS section. The second contains few info for each Computing Element. All information in this file are then digested by the Pilot code itself (in pilotTools.py).

We should:

• create another pilot.json file (with another name) where the first of the 2 parts listed above keeps the same structure that is in CS (using the functionality already present in https://github.com/DIRACGrid/diraccfg). This will also make sure that no VO-specific information is lost (this is a case, right now). See for reference [integration] Remote Pilot Logger to Tornado #6208 (comment)
• the Pilot code in pilotTools.py should be capable of looking for the new file above and interpret it correctly, if present, and fall back the old one, if not.

All new information necessary for the Pilot Logging functionality will go in the Operations/<>/Pilot CS section.

[fstagni]

Done! (since some time)