Use new API for opening android module

[helin24]

I think this fixes https://github.com/flutter/flutter-intellij/issues/7599.

I checked that I can now use Tools > Flutter > Open Android module in Android Studio, and made sure this works with a new project and an existing project. There may be more testing needed, e.g. is this supposed to work in IntelliJ also?

If we want to use this again, we should probably also re-enable a menu when a user right clicks the android subdirectory, and update comments related to https://github.com/flutter/flutter-intellij/commit/dd5a521382bf20f6cfb1121851f38c398fc9dbaa