Add example for tweens animation

[Bouh]

Hi @Wend1go I remember when you have added Tween animations you have made a example for test each types of tweening.

This example is very helpful i think it should be include with the other examples.

Solution suggested

Use this file somewhere in a test folder in the GDevelop repo and move it in example folder.
#922 (comment)

[4ian]

I do think that would be a good example. To add one, creating a folder in the newIDE/app/resources/examples with a README.md is enough. Then you have to run node update-fixtures-from-resources-examples.js and node update-examples-information-from-resources-examples.js in the newIDE/app/scripts folder. Finally for the web-app I'll upload myself the necessary resources.

[TheGemDev]

I think I should do this after the solarised dark theme