CN: Extension Synchronizers section needs an overhaul

[isegall-da]

The Extension Synchronizer section goes back and forth between "private" and "hybrid", between canton console and (AFAICT made up) helm values (I can't find any evidence that the canton-participant chart supports an additionalSynchronizerConnections or synchronizerConnections value, and even the docs are inconsistent on what this made up field is called), etc.

I think this whole section needs a complete overhaul.

Some requirements AFAICT:

• I don't think we want to ever mention a "private" synchronizer that is completely disconnected from the GSync, only what is called "a hybrid" in the docs currently (i.e. a synchronizer for which at least one participant also connects to the GSync).
• be consistent on terminology. Currently it seems like the official term is "dedicated synchronizer", not "subnet", "extension" or "private sync".
• remove any hallucinated helm value.
• clarify that in the near future, there will be cost associated with running a dedicated extension:
  • Canton Coin (CC) Fee Burning: dedicated synchronizer participants will be required to burn CC on Canton Network in the near future.
  • Global Synchronizer Compatibility: dedicated synchronizers must remain compatible with the Global Synchronizer at all times. Participants are required to adopt mandated upgrades on a timely basis to maintain network interoperability.
  • Maintained Global Synchronizer Connection: Organizations operating a dedicates synchronizer must maintain a persistent connection to the Global Synchronizer for accounting and settlement purposes. This connection is the mechanism by which fees are calculated and CC burn obligations are fulfilled.