Add service announcement on startup of responder

[CaptChrisD]

Adding Service Announcements to be compliant with Section 8.3 of mDNS standard (https://datatracker.ietf.org/doc/html/rfc6762#section-8.3)

Excerpt:

The second startup step is that the Multicast DNS responder MUST send
   an unsolicited Multicast DNS response containing, in the Answer
   Section, all of its newly registered resource records (both shared
   records, and unique records that have completed the probing step).
   If there are too many resource records to fit in a single packet,
   multiple packets should be used.

Resolves #169

[CaptChrisD]

This does function in announcing services on boot up of a device but this is VERY ROUGH and not complete.

Need guidance on current path or other possible solutions

[fhunleth]

It looks like I need to dig into this a little. Give me a bit and I'll get back.