Node-API performance

### What is the problem this feature will solve? Improve performance when creating large V8 objects which is **critical since these must always be created on the main thread, blocking the event loop.** Currently, the overhead of each method is very significant - especially for the primitive operations such as simply setting a property. As a very typical example of the current problem, you can consider these two methods for setting a property on an object: ```cpp napi_status napi_set_property(napi_env env, napi_value object, napi_value key, napi_value value); napi_status napi_set_named_property(napi_env env, napi_value object, const char* utf8name, napi_value value); ``` Naively, one expects that using the first one will be faster when the `key` is already UTF-16. However calling this method requires to first call `napi_create_string_utf16` and the combined overhead of the two calls offsets the single call of the second method when the key is not very long (which is usually the case). ### What is the feature you are proposing to solve the problem? ~~Step 1: `napi_set_named_property` that takes UTF-16~~ (not needed, see below) Step 2: Methods that can create in one call a whole array/object from a C data structure - ~~especially ones for strings already encoded in UTF-16~~ ### What alternatives have you considered? _No response_