LVN QR Code generator for LVN apps

[bcardarella]

Proposal:

LiveViewNative.qr_code(url)

This will return a SVG of a LVN qr code which app developers can use in their own applicaiton development process.

[bcardarella]

Code spike from @carson-katri https://gist.github.com/carson-katri/ad5c7e4dadbd2af97516b3d7c9bf369f

We'll want to support outputting to command line but also include a function component to inject into a web app

For the mix tasks we'll want:

> mix lvn.go swiftui`

which would call: mix lvn.swiftui.go and that task should be defined in the SwiftUI client an this would call back into the QR generator in Mix.Tasks.Lvn.Go or it would simply define the URL that the generator uses.

For the function component we define <.lvn_go_qr_code format="swiftui" />

Although it would be better if we could just generate a single URL that would then re-route to the correct app store page based upont he device that is being used.