Handlemap error reproduction

[krisbitney]

This PR contains a minimal test testSubsequentSubInvokes that reproduces the exception:

uniffi.polywrap_native.FfiException$InvokeException: uri=wrap://embed/asyncify, method=subsequentInvokes, err=``RuntimeError: __wrap_abort: Error loading wrapper, uri: wrap://ens/memory-storage.polywrap.eth: `Failed to create wrapper: ``java.lang.AssertionError: Handle map is not returning the object we just placed there. This is a bug in the HandleMap.```

The reproduction uses the Asyncify test wrap: https://github.com/polywrap/wrap-test-harness/tree/master/cases/asyncify

It invokes this method: https://github.com/polywrap/wrap-test-harness/blob/master/cases/asyncify/implementations/rs/lib.rs#L85

Which subinvokes this plugin: https://github.com/polywrap/kotlin-client/blob/main/src/commonTest/kotlin/MemoryStoragePlugin.kt

I also included three additional tests:

• testSubsequentSubInvokesToWrapper repeatedly subinvokes a Wasm wrapper
• testSubsequentInvokesToPlugin repeatedly invokes a plugin directly
• testSubsequentInvokesToWrapper repeatedly invokes a Wasm wrapper directly

These tests do not encounter any exceptions. They are included to demonstrate that the error occurs when subinvoking a plugin.