tls: make `tls.connect` accept port and host in `options`

Previous API used form:

    tls.connect(443, "google.com", options, ...)

now it's replaced with:

    tls.connect({port: 443, host: "google.com", ...}, ...)

It simplifies argument parsing in `tls.connect` and makes the API
consistent with other parts.

Fixes #1983.