Add dns-account-01 support to chisel2

[sheurich]

This change adds dns-account-01 support to the chisel2 tool for Pebble integration testing.

The enhancement to the Python acme library in https://github.com/certbot/certbot/pull/9887 is a prerequisite for this change.

Note that the existing challtestsrv library and commands are already compatible with the dns-account-01 method using /set-txt and /clear-txt with the updated authorization domain name.