Implement SuffixMatchTree::getBestMatch() to get the name that matched

[rgacogne]

Short description

This PR adds a new method, SuffixMatchTree::getBestMatch() making it possible to know against which name from a SuffixMatchTree we matched.
It also adds lua bindings for that method in dnsdist, as well as bindings for a few more DNSName methods.

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[rgacogne]

CI failure is unrelated (Google is not being cooperative with regard to ALIAS resolution).