All developer test suite examples use the engine

[HexaField]

the developer test suite has a bunch of old examples which no longer work - we need to re-create these from scratch to use the engine properly

this means using createEngine and using ECS systems, without using custom logic copied from the codebase

[rondoor124]

We updated the avatar retargeting example using our ECS system. https://github.com/XRFoundation/XREngine-development-test-suite/pull/7