Allow old and new API response for OPNsense Plugin

[blablup]

CLOSES #2480

[auto-comment]

First, never send a PR to master branch, it will never be accepted. Please send to the dev branch instead.
If this is a PR to support new DNS API or new notification API, please read this guide first: https://github.com/acmesh-official/acme.sh/wiki/DNS-API-Dev-Guide
Please check the guide items one by one.
Then add your usage here: https://github.com/acmesh-official/acme.sh/wiki/dnsapi

[blablup]

It is an or. so either it is ","allownotifyslave":{"":{[^}]*}}" or it is only the ",". Use a ")?" would also work, I don't use that often, don't know why.