Integrate physics library via WASM

Now that we support WASM on all the targets, we should try to make an integration here.

Maybe here a ECS would help. Since WASM calls are slow, we should consider making one single call or a few calls per frame.
So we could use a memory buffer doing the requested operations, and uploadingthe changes per frame, or using the WASM memory as a way to back up the objects (when supported for example in the JVM and JS).

Since I don't have experience with ECS. Let's invoke @jobe-m and @Quillraven

Do you folks think this is doable with Fleks?

With this interface: https://github.com/korlibs/korge/blob/cc9f37efe745c776957c0a69989f3733300fa1f5/korge-core/src/common/korlibs/wasm/WASMLib.kt#L9-L56

The idea would be to:
```kotlin
// Once
val xyAddress = wasm.malloc(elementCount * 4 * 2)
// ...

// Per frame
wasm.writeBuffer(xyAddress , xyBuffer) // Copy ECS data into WASM memory
wasm.invokeFunction("doSimulation")
wasm.readBuffer(xyAddress , xyBuffer) // Read-back ECS data into WASM memory
```

So one write, one call and one read per frame, which might be fast enough.
But not sure if that's doable or how ECS works?

Start with the referenced korge-core/src/common/korlibs/wasm/WASMLib.kt lines 9-56, then investigate how Fleks ECS data could be exchanged with WASM. There are no tests or implementation files named in the issue; done would require a concrete, agreed integration approach or prototype covering the per-frame buffer, call, and read-back flow.

Written by the indexing model from the issue text.