Part of https://github.com/flutter/flutter/issues/130277
Without this, if a user runs an app that has plugins that call method channels with the `preview` device, the app will build successfully, however, they will get a runtime error when their dart code tries to call the method channel that does not exist in the native build (which was pre-built and thus does not include the plugin code).
This change adds a validation when injecting plugins that will tool exit if the device-id is `preview` and their project contains plugins with method channels.
Fixes https://github.com/flutter/flutter/issues/130277
This PR does two things:
1. introduce a hidden `flutter build _preview` command, that will build a debug windows desktop app and copy it into the SDK's binary cache. This command is only intended to be run during packaging.
2. introduce a new device type, called `PreviewDevice`, which relies on the prebuilt desktop debug app from step 1, copies it into the target app's assets build folder, and then hot reloads their dart code into it.
