Updating multiple instances

### Description

Currently you can update the image of Node-Red, but it would helpful to be able to update the code/flow also.

So, if there are multiple instance of Node-Red using the same template code/nodes, you could update them all.

Requested by:

https://app-eu1.hubspot.com/contacts/26586079/record/0-2/10189549510

### Which customers would this be available to

Team + Enterprise Tiers (EE)

### Have you provided an initial effort estimate for this issue?

I can not provide an initial effort estimate

Start by tracing the existing image-update path for Node-Red instances and how template code and nodes are represented. Define how one template change should propagate to multiple instances, including supported tiers and a clear way to verify that all affected flows are updated.

Written by the indexing model from the issue text.