Add an "Ellipse movement" extension example

[D8H]

Show how to use the "Ellipse movement" extension to move a player in a snake-like game.

Extension PR:

• Ellipse movement rework GDevelop-extensions#591

[github-actions]

Preview the game(s) changed or added in this Pull Request

• https://editor.gdevelop.io?project=https://raw.githubusercontent.com/GDevelopApp/GDevelop-examples/star-seeker/examples/star-seeker/star-seeker.json

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This is an automatic message displaying links to the games in this PR - double check the JSON in case of doubt.

[github-actions]

Images automagically compressed by Calibre's image-actions ✨

Compression reduced images by 2.2%, saving 72 bytes.

Filename	Before	After	Improvement	Visual comparison
examples/star-seeker/assets/Red playerShip (1).png	2.65 KB	2.61 KB	-1.3%	View diff
examples/star-seeker/assets/Silver star.png	637 bytes	601 bytes	-5.7%	View diff

4396 images did not require optimisation.

[tristanbob]

Summary

This is a great example of a one-button game and you did it with only 2 events! Bravo!

Suggestions

• Use CameraBorderLeft() and similar expressions instead of 0 and SceneWindowWidth. It's more obvious and it works even if the camera moves.
• Use Object.Width() / 2 instead of 32 so people understand where the number came from (and it still works if they change the object image)

[D8H]

• Use CameraBorderLeft() and similar expressions instead of 0 and SceneWindowWidth. It's more obvious and it works even if the camera moves.
• Use Object.Width() / 2 instead of 32 so people understand where the number came from (and it still works if they change the object image)

Thanks, I did the changes.