JS OOP: add Frogger practice

[OleksiyRudenko]

This task is actually a minimally tweaked original project description.

All resources linked (video, tech requirements, repo) are publicly accessible.

We may want to translate js-oop-frogger.md and, possibly, original tech requirements to Ukrainian at some point.

Motivation:

• seeing gap in tasks progress just breaks my heart
• students will have a nice and visually appealing project on their portfolios
• students will learn SOLID and OOP principles (also DRY and KISS if haven't yet)

Please review.

Resolves #411

P.S. We may also encourage students to change imagery to make the games more diverse. Some will make it to our twitter

[suchov]

💥