core.certmanager: Support 'use_dane' setting to enable DANE support
Removes the need to enable DANE with two separate settings.
Previously you had to also set `ssl = { dane = true }` to activate DANE
support in LuaSec and OpenSSL.
Thanks for your interest in contributing to the project!
There are many ways to contribute, such as helping improve the
documentation, reporting bugs, spreading the word or testing the latest
development version.
You can find more information on how to contribute at <https://prosody.im/doc/contributing>
See also the HACKERS and README files.