Enhance Top Down sample

[DarkRewar]

Description

For now, the top down sample uses a capsule as character. And the documentation is quite poor. We should enhance all of that.

Process

First, the sample should include a 3D model with animations (that would be used by others movement sample). This model will be added to the top down sample and top down player to let users know how to implement properly the component.

Then, we should upgrade the documentation by adding gifs of the sample.