Migrated dicee-flutter stub project to support Flutter 2.2.3

[tigerjoy]

The stub project was migrated to mitigate the errors that were being displayed when was used a template to build Flutter projects.

The migration instructions were followed from https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects

This stub was tested to be running on an Android Emulator.

[samarth-agrawal-86]

Course instructor should merge this pull request. I don't know why there is no action from them

[vialcollet]

Great work. Thanks a lot for this @tigerjoy

[vialcollet]

Here is a set of instructions to pull this:

git clone https://github.com/londonappbrewery/dicee-flutter.git
cd dicee-flutter
git pull origin pull/33/head

[philippkeller]

this PR still works out of the box! Thanks a lot for providing it, @tigerjoy . I also did a PR for the previous project which is not yet accepted. But even before the merge, the git savvy people can profit from it 🙏

[spinoza1791]

Here is a set of instructions to pull this:

git clone https://github.com/londonappbrewery/dicee-flutter.git
cd dicee-flutter
git pull origin pull/33/head

lifesaver! thx