Add Everbridge for contact point

[justinhauer]

I am looking to have the built-in alert manager within grafana send to the everbridge endpoint, but due to the issue here:
https://community.grafana.com/t/alerting-webhook-contact-point-authorization-header/73220, I am unable to do so because of custom headers. I see the following PR has been open for a long while and hasn't merged in. this could also work but there's no OOTB solution for me to send to this endpoint currently. #135.

How can I best request the ability to either increase the flexibility of the web hook contact point, or add an additional one?

Cheers!