dgram: support Uint8Array input to send()

Fixes: https://github.com/nodejs/node/issues/11954
Refs: https://github.com/nodejs/node/pull/11961
PR-URL: https://github.com/nodejs/node/pull/11985


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>