chore(napi): make napi_register_module_v1 pub

[MarkusJx]

I'd like to use classes created by napi-rs inside a Node.js instance which is created using rust-nodejs. For this to work, the classes need to be exported to the node runtime using napi::bindgen_prelude::napi_register_module_v1, which is currently not accessible from outside its module.

This PR makes this method accessible from outside its module.

Code I'm using to initialize napi-rs modules inside a node vm created by rust-nodejs

If someone is interested in how I'm using the napi_register_module_v1 method:

use napi::bindgen_prelude::napi_register_module_v1;
use napi::sys::{napi_env, napi_value};
use napi::Env;
use nodejs::run_raw;
use std::ffi::c_void;
use std::ptr::null_mut;

static ONCE: Once = Once::new();

unsafe fn run_napi<F: for<'a> FnOnce(Env)>(f: F) -> i32 {
    static mut MODULE_INIT_FN: *mut c_void = null_mut();

    let mut module_init_fn = Some(f);
    MODULE_INIT_FN = (&mut module_init_fn) as *mut Option<F> as _;

    unsafe extern "C" fn napi_reg_func<F: for<'a> FnOnce(Env)>(
        env: napi_env,
        exports: napi_value,
    ) -> napi_value {
        ONCE.call_once(|| {
            napi_register_module_v1(env, exports);
        });

        let module_init_fn = (MODULE_INIT_FN as *mut Option<F>).as_mut().unwrap();
        let module_init_fn = module_init_fn.take().unwrap();
        MODULE_INIT_FN = null_mut();
        module_init_fn(Env::from_raw(env));

        exports
    }

    run_raw(napi_reg_func::<F> as _)
}