JDC fallback engine does not have a visual representation

[lucasbalieiro]

We need to think on how to handle the fallback scenarios of JDC:

• When one of the upstreams fails the fallback upstream is called
• If all upstream fails the JDC falls back to solo mining.

From the sv2-ui prespective we can only know this from parsing the logs.

As an example, the AxeOS just accept two upstreams and if the main one fails it pops up a yellow banner: