Internal name resolution over UDP with fallback to TCP

[DL6ER]

What does this implement/fix?

This is a follow-up PR improving #1976 for edge-cases where upstream servers (can be local routers, especially in the context of conditional forwarding) are not capable to doing DNS over TCP. The PR changes the internal name resolver use UDP by default, but actively detect UDP DNS truncation (commonly seen in conjunction with DNSSEC) and appropriately fall back to TCP for corresponding queries.

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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• [x] The code change is tested and works locally.
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[rdwebdesign]

Tested using the old (crap) router and it is working as expected. No more connection errors.