Update Wasm3, make use of exciting new API

[vshymanskyy]

With latest Wasm3 (v0.5.0), new API is available which fixes many things in the public API:

• Exported function signature introspection
• Introspection of imported functions (see _ctx argument)
• Public api for calls with raw arguments (instead of strings)
• Public API to get return values
• Support recursive m3_Call invocation. I.e. calling exported function from within imported function callback.
• m3_RunStart can be used to force the module initialization.

I think all this can greatly help your bindings implementation. @Veykril please let me know it you need any other public API, or have any ideas!

This is already implemented in Python bindings, you can use it as a reference: https://github.com/wasm3/wasm3/blob/master/platforms/python/m3module.c

[jimpo]

I have prototyped this as I was running into issues with the old version of Wasm3 currently supported by this crate. I use only the types and functions exposed in wasm3.h and m3_api_wasi.h (if the wasi feature is enabled). However, this crate makes heavy use of internal structs, and so not all exposed functionality is available using only the public API. In particular, I had to remove this functions:

• Function::import_module_name (The name of the import module of this function)
• Module::function (Looks up a function by its index in this module)
• Runtime::find_module (Searches for a module with the given name in the runtime's loaded modules)
• Runtime::modules (Returns an iterator over the runtime's loaded modules)
• Runtime::resize_memory (Resizes the number of allocatable pages to num_pages)
• Runtime::stack and stack_mut (Returns the stack of this runtime)

So we could either add to the wasm3 API to keep these or remove them from the Rust API. I'd be happy to open a PR with my changes, which has bindings to the v0.5.0 release.