WASM bindings in ACT (through emscripten)

[vijaiaeroastro]

• This PR introduces WASM bindings for ACT.
• The first version of this generator was originally implemented in Python: https://github.com/3MFConsortium/lib3mf_emscripten with the goal of creating WASM bindings for lib3mf.
• The same functionality has now been ported and tested in ACT, and is designed to be generic and reusable.
• All examples from the original lib3mf_emscripten repository work seamlessly with the bindings generated via ACT.

Key Features

• Automatically generates wrapper structs for each native struct.
• Creates wrapper methods when a struct is used as a method argument.
• Handles non-const reference parameters by generating alternate wrapper methods that return a JavaScript object (since direct manipulation of non-const refs is not supported by Emscripten).
• Most functions that take Pointers to class objects use a wrapper class called classParam in ACT. We detect these and automatically make it work inside bindings. However, users can simply use pointers in Javascript. Here is an example

const gyroidFunction = model.AddImplicitFunction();
gyroidFunction.SetDisplayName("gyroid");

// Add input position
const inputPos = gyroidFunction.AddInput("pos", "position", lib3mf.eImplicitPortType.Vector);

// Add decompose vector node
const decomposePos = gyroidFunction.AddDecomposeVectorNode("decomposePos", "decompose pos", "group_a");
  
// Link both
gyroidFunction.AddLink(inputPos, decomposePos.GetInputA()); // <--- Note this line

In the highlighted line above AddLink is actually supposed to have a signature like this in Cpp

void CImplicitFunction::AddLink(classParam<CImplicitPort> pSource, classParam<CImplicitPort> pTarget)
{
  Lib3MFHandle hSource = pSource.GetHandle();
  Lib3MFHandle hTarget = pTarget.GetHandle();
  CheckError(lib3mf_implicitfunction_addlink(m_pHandle, hSource, hTarget));
}

However, this cannot be implicitly constructor in WASM. So, we have a wrapper like this

static void wrap_ImplicitFunction_AddLink(CImplicitFunction &self, PImplicitPort& Source, PImplicitPort& Target) {
    self.AddLink(classParam(Source), classParam(Target));
}

This is automatically generated for all functions making it easy to write JS friendly code.

Known Issues

• classParam<T> is used in many methods in the volumetric extension.
• callBack functions are not supported yet