Let payment gateways prefer webhook URLs without query parameters

[Mosnar]

What are you trying to do?
I built a payment gateway for Authorize.Net when Commerce 2 first came out. I want to add webhook support now; however, for some ridiculous reason, I am not allowed to enter a webhook URL into Authorize.Net with query parameters.

What's your proposed solution?
It would be nice if I could set a property to tell Craft to use a routed webhook URL instead (displaying the appropriate URL in the gateway UI).
The current URL looks like this:
mysite.com/index.php?p=actions/commerce/webhooks/process-webhook&gateway=3

Perhaps an alternative could be:
mysite.com/commerce/webhooks/gateway-handle/process-webhook

[lukeholder]

We just added support for a non parameterised URL to process webhooks for the next release of Commerce.

In your gateway class you need to override the base gateway getWebhookUrl() to return a URL in this format:

http://craft-commerce3.test/commerce/webhooks/process-webhook/gateway/4 -
With the 4 being replaced by the current Gateway ID.

You would do something like this in your method:

UrlHelper::baseSiteUrl('commerce/webhooks/process-webhook/gateway/'.$this->id);