Allow to manually change the node URL

[Senyoret1]

@gz-c This should be done only for the Electron wallet or also for the web wallet?

[gz-c]

Both

[gz-c]

The goal is, instead of requiring every fiber coin to deploy their own web wallet, they would only need to deploy a public node. Then users can load the public node's URL to interact with that wallet.

We'll be adding an endpoint to the node to expose some configuration data that can be used to customize the wallet display, but this isn't ready yet. It's not necessary either.

This also allows a motivated user to use their own public node, instead of relying upon ours.