Do not destroy the whole app if the connection has an error

[AgeManning]

Currently if there is a fault in the connection, the backend is destroyed.

This PR keeps the application alive in the event there is a fault and attempts reconnects every 30 seconds.

[chong-he]

Done a testing on this. It works, Siren doesn't just error out immediately if connection breaks, it shows a screen. But the screen message only appears very quickly (maybe 0.1s) and then disappear immediately. This one:

It will be great if this message can stay on (like a x on the top right corner for user to close it)

Also, in my testing, I stop my beacon node, but the message says the VC

[chong-he]

Still the same issue as above, tested with the commit 5c78961

More info: if I stop the VC, the message pop up also shows VC which is correct, but stopping BN showing VC is not

[chong-he]

More info on this:

the backend is destroyed

During testing with npm run dev and npm run start in backend, once the beacon node is stopped (intentionally), the backend will stop too. The front end is still on. So I think that's the root cause (on the backend)