Update Feature Electron App

[krrprr]

Enable updating the application without manually downloading and installing a new version.

[kilrau]

Recap: idea is to use https://github.com/vercel/hazel for Win & Mac, for Linux just show the update notification with download button because there is no standardized way to load updates yet.

[kilrau]

Two things to update:

1. Electron App: display there is an app update, offer installation (see wireframe) - this is what this issue is about
2. Docker update: trigger accepting docker update prompt via api for local & remote environments: Update Feature Containers #88

[krrprr]

2. Docker update: trigger accepting docker update prompt via api for local & remote environments: Update Feature Containers #88

This actually only applies to remote environments. When the electron app is updated, the new launcher version comes with it (in case the new xud-ui version with the latest launcher is released, which should be the practice) and it defines the versions, so there is no need to update the local xud-docker environment separately. When the app is restarted, new containers are pulled and the whole environment gets updated at once.

[kilrau]

Right. Good.

How could an update of a remote environment work though if I am connecting to it via the Electron App / browser via the build-in web app of the proxy container?

[krrprr]

Right. Good.

How could an update of a remote environment work though if I am connecting to it via the Electron App / browser via the build-in web app of the proxy container?

I think the exact implementation of remote environments should be discussed and/or decided in #88.
The tricky part there is the case when the user connects to a remote environment via the xud-ui app - the versions have to be compatible. Have no plan for this yet.

[krrprr]

Recap: idea is to use https://github.com/vercel/hazel for Win & Mac, for Linux just show the update notification with download button because there is no standardized way to load updates yet.

Seems that https://www.electronjs.org/docs/tutorial/updates#using-updateelectronjsorg would be sufficient instead of hazel. In both ways the code-signing is required at least for macOS.

[kilrau]

In both ways the code-signing is required at least for macOS.

I am taking care of an Apple developer account today.