* Generate Android framework config

* Fix templates

* Moar templates fixing

* Minor tweaking

IDEA users sometimes want to create multiple Flutter modules
in the same IDEA project. See discussion:
https://github.com/flutter/flutter-intellij/issues/1014

In this case, we will actually have pairs of modules,
one for Flutter and one for Android. Renaming the
android module to make the relationship obvious.

But, don't delete the old file yet to avoid breaking
existing users. We can do that after the next
Flutter plugin release.

Generates an android.iml file and a package-level library for flutter.jar.

Does not set up an Android SDK in IDEA; this isn't possible with a
template-based approach. But IDEA shows a clear warning, so the
user can fix this by setting the SDK.

(When creating a Flutter project from within IDEA, we can fix this up
afterwards in the plugin.)