Llt 5309 integrate multicast components

[ThrasherLT]

Problem

All the separate parts of starcast (see RFC LLT-0060) are ready to be integrated into Telio.

Solution

This PR integrates all the separate starcast parts (virtual peer, transport and nat) into libtelio.
You can see the doc rs in code of every separate component to understand how they're supposed to be integrated into telio.

The Nat-Lab test for multicast is being implemented with a separate PR, so this one is untested yet.

☑️ Definition of Done checklist

• Commit history is clean (requirements)
• README.md is updated
• Functionality is covered by unit or integration tests

[LukasPukenis]

As a reviewer I can't effectively review because while the PR description tells what this PR does(I understand words), it doesn't add any context, thus starcast for me is just a buzzword :/ It would really help to have more information what it is

[mathiaspeters]

thus starcast for me is just a buzzword :/

In a nutshell, starcast (*cast was the working name to cover multicast and broadcast as one word, and it could be pronounced as starcast if you say it as an actual word) is the meshnet implementation of multicast. I guess this is a general problem with "integration PRs" where you need to understand the components that are being integrated to properly understand and review the integration work. For more background you can check RFCs LLT-0060 and LLT-0047, or if it makes more sense, this could be a candidate for a review meeting or something like that to make it easier for you and to share some knowledge

[packgron]

Few nit's

[mathiaspeters]

+1

[packgron]

+1.0