TELCU-25 Proper SRV lookup, and keeping fallback options

[genseric-ghiro]

Summary

• Instead of looking up IP by default, start with SRV records which solves the issue of custom ports (this is the correct SIP behavior, and what's implemented in emiago/sipgo 1.4.0)
• Instead of returning a single IP/Port, return a list of them sorted by priority. This way, other addresses can be tried if the first one can't be reached

Tests

• Unit tests