OnPrem EdgeAgent / OnPrem Device Manager.

### Description

When looking at FlowForge and tyring to figure out if is a good fit for my user case, i see the need for som sort of OnPrem Edge Device Manager.
Currently Each Device is communicating directly with flowforge, and that is fine when all devies have internet. But in cases where you want to limit the amount of devices allowed to acces internet, then this approach does fit with how the Device Agent Currenly work.. As some of my customers users, wants to controll their whole network and want to air gap it as much as possible.

similar to how Azure Iot Edg Device works. Where each Iot Device talk trough the IotHub, and that allows for offline capabilities and the the devices themself does not neccesarily have internet access.

**Short explanation around my setup**
Currenlty my setup consists of 24 Plants,
Where each plant have 1 Master computer that gives user acces to view and manage the system. and this also usualy ahve internett access.
as well as x amount of raspberry Pis, usualy around 40, that works standalone, but can communicate with the master to be controlled or send/recive information. but these does not always have intenrett access.

So overall i have 24 Masters that runs and around 940 Raspberry pis running on different locations.

Usualy the Masters are easy to update, they have internett and rund Containers.,
The Pis are sometimes harder, and can be updated by beeing on the network and iterating over alle the PI's and updating the flow torugh the Node-Red Api. In cases where there is required to update the node-red or some nodes versions. Then usualy the PI's sd card are replaced, but that is timeconsuming and sometimes difficult.

**Feature Request**

- Create an EdgeAgent that can act as the local device manager, beeing resposible for downloading the latest device snapshot and install on the devices on the newtork.
- The EdgeAgent could include an offline mode where a file is uploaded to the agent using USB and then be deployed out to all devices.
- Both cases assumes that the snapshot includes all nessecary files for "offline" instalation.
- When installing the EdgeAgent it could look for all OnPrem Devices that have the Device Agent and update their configuration to talk to/trough the OnPrem EdgeAgent.
- EdgeAgent have local dashboard to view the OnPrem Devices,


This is my initial tought on the process and is needed to discuss further if this is a possibility and how it could possibly work.

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

I am not a FlowForge team member