Add Billing webhook

[dborovcanin]

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

I want the Auth service to send a webhook to a remote Billing service.

Describe the feature you are requesting, as well as the possible use case(s) for it.

Billing is another policy enforcement point, only for different purposes. I want the Auth service to be able to issue a webhook to it so we can enforce billing policies alongside authorization.

Indicate the importance of this feature to you.

Must-have

Anything else?

No response