notifier plugins: custom domain name for reports

[Igor]

Is your feature request related to a problem? Please describe.

We would like to have our reports available via a custom domain name which has cloudflare authentication enabled.

Describe the solution you'd like

The only thing to make this work which seems to be missing is a configuration option for the notifier plugins (GitHub notifier and Slack notifier) to use a custom domain instead of the standard one (based on the bucket name).

Sorry if it's available and I've missed how to achieve this. Also, with a bit of guidance I can try creating a PR to add a solution.

[Igor]

Answering to myself: there is a customDomain option available for the S3 publisher plugin, it's used to pass URLs to the notifier plugins, so it solves the issue.
It was not clear from the beginning that the issue should be tackled on the publisher plugins side.