Allow local (LAN) access to a device as a config option

[robmarcer]

Description

As a backup to being able to access a device's editor from FlowFuse, it would be helpful to be able to access the editor directly.

This has been requested by this existing customer - https://app-eu1.hubspot.com/contacts/26586079/record/0-1/503903

This will allow a user to make changes to their flow in an emergency situation where their network connection to FlowFuse is unstable or offline.

We would need to consider how the local connection to these devices is secured.

I would suggest that local access is disabled by default but can be switched on by editing the device's device.yml

[MarianRaphael]

See FlowFuse/flowfuse#2855

[robmarcer]

This has also been discussed with https://app-eu1.hubspot.com/contacts/26586079/record/0-1/4909801 & https://app-eu1.hubspot.com/contacts/26586079/record/0-1/1956

[joepavitt]

Security is managed by FF OAuth, but a strong use case here is the ability to access the editor if the device has lost network connection. Open point of discussion here is how we handle the security of the offline access use case.