[Notifications] Improving webhook notifications (#6965)

* worker setup

* fix tests

* start worker

* graceful worker drain

* retry queue

* migrate queue to watermill

* adding filters and improvements

* add the event type to the webhook message

* eliminating redundant JSON serialization

* resolve review comments

* trigger actions

* fix tests

* typo fixes

* read max_backoff_seconds from config

* add more context to the dead letter

* close the http response on errors

* drain the http response body in case not empty

* eliminate exported typesπ

go.mod

@@ -123,6 +123,7 @@ require (
 
 require (
 	github.com/Jille/raft-grpc-transport v1.6.1
+	github.com/ThreeDotsLabs/watermill v1.4.7
 	github.com/a-h/templ v0.3.906
 	github.com/arangodb/go-driver v1.6.6
 	github.com/armon/go-metrics v0.4.1
@@ -162,6 +163,12 @@ require (
 
 require github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88 // indirect
 
+require (
+	github.com/cenkalti/backoff/v3 v3.2.2 // indirect
+	github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88 // indirect
+	github.com/lithammer/shortuuid/v3 v3.0.7 // indirect
+)
+
 require (
 	cel.dev/expr v0.23.0 // indirect
 	cloud.google.com/go/auth v0.16.2 // indirect