fs: fix error when writing buffers > INT32_MAX

This reverts c380ee67.
uv_fs_write returns an int, so it is not possible to ask
it to write more than INT32_MAX.

Instead, validate 'length' is an int32 in JS to avoid
the assertion failure.

PR-URL: https://github.com/nodejs/node/pull/38546


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>