Support --auth-token as --auth-password for providers which don't support token auth

[taxilian]

I've recently been using lexicon for ACME DNS-01 solvers, both in opnsense and with a kubernetes cert-manager webhook that I wrote in the last few days. Both ran into an issue when I tried using the henet provider where they were expecting auth to use --auth-token but it needed --auth-password.

I was able to update my webhook to let you pass a field indicating if it's a password instead of a token, but it would probably fix a bunch of unknown bugs in systems like that if providers which only supported password would accept --auth-token and just treat it as a password. I don't know which all providers support which, so I don't know if there are other complications to doing that, but now I'm going to have to dig into the opnsense plugin to figure out if there is a way to get it to work with dns providers (like henet specifically) which don't support --auth-token :-/

[taxilian]

Looking through it seems like this probably would have to be a per-provider change; would a PR for that be accepted?

[adferrand]

For sure, I will happily review it!