n-api: improve consistency of how we get context

Refs: https://github.com/nodejs/node-addon-api/issues/764


Improve the consistency of how we get a context
when needed. We generally used env->context() in N-API
but there were are few exceptions that this PR addresses.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: https://github.com/nodejs/node/pull/36068


Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Gabriel Schulhof <gabriel.schulhof@intel.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>