feat: Add notify plugin for opsgenie

[seagleNet]

Add notify plugin for OpsGenie.

The plugin has been implemented with full configuration support for API key, region selection and priority mapping for acme.sh's 3 return codes.
Notifications are de-duplicated on opsgenie by the alias (acme.sh + hostname + subject + date).

[github-actions]

Welcome
Please make sure you've read our Code-of-conduct and add the usage here: notify.
Then reply on this message, otherwise, your code will not be reviewed or merged.
We look forward to reviewing your Pull request shortly ✨

[seagleNet]

Welcome Please make sure you've read our Code-of-conduct and add the usage here: notify. Then reply on this message, otherwise, your code will not be reviewed or merged. We look forward to reviewing your Pull request shortly ✨

Hi! I've reviewed the code of conduct and add the usage to the wiki: https://github.com/acmesh-official/acme.sh/wiki/notify/08cc018305500dd75aba13d697f21a22b564b779