[FEAT][Rust] Support Rust stubgen.

[Seven-Streams]

This PR is based on #434 to support stubgen in Rust. This PR fixed issues such as the module lifecycle issue on Windows, lint problem, PATH resolution, and so on.

TODO List:

• further tests, including e2e and modules.
• further human reviews.
• document alignment.

[gemini-code-assist]

Code Review

This pull request introduces a Rust stub generator (tvm-ffi-stubgen) that generates Rust stubs from TVM-FFI reflection metadata, alongside supporting changes in tvm-ffi and tvm-ffi-sys such as a new Map collection, subtyping casting utilities, and macro expansions. The review feedback identifies three critical issues in the code generator: a potential null pointer dereference when traversing type ancestors, a double Obj suffix bug in parent type formatting, and an invalid non-primitive cast in the generated method wrappers.

[gemini-code-assist]

In for_each_field_info, info.type_acenstors is dereferenced via .add(i as usize) without checking if the pointer is null. If info.type_depth > 1 but info.type_acenstors is null, this will cause undefined behavior or a crash. A null check should be added before accessing info.type_acenstors.

    unsafe {
        if !info.type_acenstors.is_null() {
            for i in 1..info.type_depth {
                let parent = *info.type_acenstors.add(i as usize);
                if parent.is_null() {
                    continue;
                }
                let parent = &*parent;
                if parent.fields.is_null() || parent.num_fields <= 0 {
                    continue;
                }
                let parent_fields = 
                    std::slice::from_raw_parts(parent.fields, parent.num_fields as usize);
                for field in parent_fields {
                    callback(field);
                }
            }
        }

[gemini-code-assist]

If parent_key is not found in _type_map, parent_rust is formatted with the Obj suffix appended. However, at line 961, format!("{}Obj", types_path) is called, which appends Obj again. This results in a double Obj suffix (e.g., TestingTestCxxClassBaseObjObj), causing a compilation error in the generated code. The fallback should return the base type name without the Obj suffix.

Suggested change

	let parent_rust = _type_map
	.get(parent_key)
	.cloned()
	.unwrap_or_else(|| format!("{}Obj", sanitize_ident(parent_key, IdentStyle::Type)));
	let parent_rust = _type_map
	.get(parent_key)
	.cloned()
	.unwrap_or_else(|| sanitize_ident(parent_key, IdentStyle::Type));

[gemini-code-assist]

The cast self as &tvm_ffi::object::ObjectRef is an invalid non-primitive cast between different struct references in Rust and will cause a compilation error in the generated code. Since Self implements AnyCompatible (via the derived AnyCompatible trait), AnyView::from(self) is completely valid and does not require any cast.

Suggested change

	"{} views.push(AnyView::from(self as &tvm_ffi::object::ObjectRef));",
	"{} views.push(AnyView::from(self));",