Add tests for webhook and fix some webhook bugs (#33396) (#33442)

This PR created a mock webhook server in the tests and added integration
tests for generic webhooks.
It also fixes bugs in package webhooks and pull request comment
webhooks.

This also corrected an error on the package webhook. The previous
implementation uses a `User` struct as an organization, now it has been
corrected but it will not be consistent with the previous
implementation, some fields which not belong to the organization have
been removed.

Backport #33396
Backport part of #33337

modules/webhook/structs.go

@@ -26,6 +26,7 @@ type HookEvents struct {
 	Repository               bool `json:"repository"`
 	Release                  bool `json:"release"`
 	Package                  bool `json:"package"`
+	Status                   bool `json:"status"`
 }
 
 // HookEvent represents events that will delivery hook.