Restructure webhook module (#22256)

Previously, there was an `import services/webhooks` inside
`modules/notification/webhook`.
This import was removed (after fighting against many import cycles).
Additionally, `modules/notification/webhook` was moved to
`modules/webhook`,
and a few structs/constants were extracted from `models/webhooks` to
`modules/webhook`.

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

services/convert/convert.go

@@ -22,13 +22,11 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unit"
 	user_model "code.gitea.io/gitea/models/user"
-	"code.gitea.io/gitea/models/webhook"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/gitdiff"
-	webhook_service "code.gitea.io/gitea/services/webhook"
 )
 
 // ToEmail convert models.EmailAddress to api.Email
@@ -242,38 +240,6 @@ func ToGPGKeyEmail(email *user_model.EmailAddress) *api.GPGKeyEmail {
 	}
 }
 
-// ToHook convert models.Webhook to api.Hook
-func ToHook(repoLink string, w *webhook.Webhook) (*api.Hook, error) {
-	config := map[string]string{
-		"url":          w.URL,
-		"content_type": w.ContentType.Name(),
-	}
-	if w.Type == webhook.SLACK {
-		s := webhook_service.GetSlackHook(w)
-		config["channel"] = s.Channel
-		config["username"] = s.Username
-		config["icon_url"] = s.IconURL
-		config["color"] = s.Color
-	}
-
-	authorizationHeader, err := w.HeaderAuthorization()
-	if err != nil {
-		return nil, err
-	}
-
-	return &api.Hook{
-		ID:                  w.ID,
-		Type:                w.Type,
-		URL:                 fmt.Sprintf("%s/settings/hooks/%d", repoLink, w.ID),
-		Active:              w.IsActive,
-		Config:              config,
-		Events:              w.EventsArray(),
-		AuthorizationHeader: authorizationHeader,
-		Updated:             w.UpdatedUnix.AsTime(),
-		Created:             w.CreatedUnix.AsTime(),
-	}, nil
-}
-
 // ToGitHook convert git.Hook to api.GitHook
 func ToGitHook(h *git.Hook) *api.GitHook {
 	return &api.GitHook{