Flow control in CB updates

[fgalan]

It would be great if IOTAs could also benefit from flow control feature in CB, enabling the ?option=flowControl in the updates sent to ContextBroker. Maybe this should be a configuration parameter, with the usual "tree layers":

• General config in config.js / env var
• Group
• Device

the latter overriding the former.

This would help ETL integrations, when the ETL sends information via IOTA.

[mapedraza]

As discussed in our 2023 roadmap meeting, this feature does not have sense (NodeJS is asynchronous). Instead, it should make sense in the southbound as described here: #1420