Bohdan Mihiliev

Idea behind this PR is adopt `ShimmerState`. With ShimmerState we can support multiple states of Shimmer Widget. For example in case of my App. I need to pause shimmer animation...

I think my solution can be combined with solution in. https://github.com/hnvn/flutter_shimmer/pull/12

> Please add tests considering each state of the shimmer and check with expect Ok. Going to add tests.

> Please add tests considering each state of the shimmer and check with expect Added some tests in latest PR. Could you take a look at what do you think?

Also, make some changes and introduce an animation controller provider. To make AnimationController testable.

Pls check with new 3.1 version

@horrion I've just updated and rebuild SameFace.framework. For new updates. Probably your help may require. Cause building SameFace.framework universal framework is a `pain` for me) And anything may go wrong....

Also pls [take a look](https://cmusatyalab.github.io/openface/) on dlib ml model specification and pros/cons