Function generate_function_with_js_namespace 

pub fn generate_function_with_js_namespace(
    decl: &FunctionDecl,
    ctx: &ModuleContext,
    js_namespace: &str,
    cgctx: Option<&CodegenContext<'_>>,
    doc: &Option<String>,
    scope: ScopeId,
) -> TokenStream

Generate wasm_bindgen extern blocks for a free function inside a namespace.