[feat] Add deprecation warning for updater.dialog: true in v1

[FabianLars]

Describe the problem

In v2 we somewhat quietly got rid of the built-in dialog. This is especially unexpected for devs that didn't set the updater.dialog config at all because it defaulted to true hiding the fact that no config in v2 is vastly different in behavior.

For example one dev on discord updated many of their users to a v2 version of their app and now just noticed that those users can't receive any further updates. Very very unfortunate situation...

Describe the solution you'd like

The cli and/or compiler should print warnings.

Alternatives considered

I've already updated the migration docs with a bit of color to make this more apparent.

Additional context

No response