Consider improving behavior when changing template settings after modifying files

[oliverdunk]

Currently, changing something like the Manifest or browser version after making changes shows a prompt. You can choose to either accept the change and lose all of your own modifications or abort.

I'm not sure if this is always best - for example, you may want to turn on the polyfill and still keep your state.

Perhaps there could be a modal asking you if we should update from the template or just change the setting but keep your code? It could get annoying if we show that too often though, especially if you're changing multiple things 🤔