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>

modules/webhook/type.go

@@ -0,0 +1,95 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package webhook
+
+// HookEventType is the type of a hook event
+type HookEventType string
+
+// Types of hook events
+const (
+	HookEventCreate                    HookEventType = "create"
+	HookEventDelete                    HookEventType = "delete"
+	HookEventFork                      HookEventType = "fork"
+	HookEventPush                      HookEventType = "push"
+	HookEventIssues                    HookEventType = "issues"
+	HookEventIssueAssign               HookEventType = "issue_assign"
+	HookEventIssueLabel                HookEventType = "issue_label"
+	HookEventIssueMilestone            HookEventType = "issue_milestone"
+	HookEventIssueComment              HookEventType = "issue_comment"
+	HookEventPullRequest               HookEventType = "pull_request"
+	HookEventPullRequestAssign         HookEventType = "pull_request_assign"
+	HookEventPullRequestLabel          HookEventType = "pull_request_label"
+	HookEventPullRequestMilestone      HookEventType = "pull_request_milestone"
+	HookEventPullRequestComment        HookEventType = "pull_request_comment"
+	HookEventPullRequestReviewApproved HookEventType = "pull_request_review_approved"
+	HookEventPullRequestReviewRejected HookEventType = "pull_request_review_rejected"
+	HookEventPullRequestReviewComment  HookEventType = "pull_request_review_comment"
+	HookEventPullRequestSync           HookEventType = "pull_request_sync"
+	HookEventWiki                      HookEventType = "wiki"
+	HookEventRepository                HookEventType = "repository"
+	HookEventRelease                   HookEventType = "release"
+	HookEventPackage                   HookEventType = "package"
+)
+
+// Event returns the HookEventType as an event string
+func (h HookEventType) Event() string {
+	switch h {
+	case HookEventCreate:
+		return "create"
+	case HookEventDelete:
+		return "delete"
+	case HookEventFork:
+		return "fork"
+	case HookEventPush:
+		return "push"
+	case HookEventIssues, HookEventIssueAssign, HookEventIssueLabel, HookEventIssueMilestone:
+		return "issues"
+	case HookEventPullRequest, HookEventPullRequestAssign, HookEventPullRequestLabel, HookEventPullRequestMilestone,
+		HookEventPullRequestSync:
+		return "pull_request"
+	case HookEventIssueComment, HookEventPullRequestComment:
+		return "issue_comment"
+	case HookEventPullRequestReviewApproved:
+		return "pull_request_approved"
+	case HookEventPullRequestReviewRejected:
+		return "pull_request_rejected"
+	case HookEventPullRequestReviewComment:
+		return "pull_request_comment"
+	case HookEventWiki:
+		return "wiki"
+	case HookEventRepository:
+		return "repository"
+	case HookEventRelease:
+		return "release"
+	}
+	return ""
+}
+
+// HookType is the type of a webhook
+type HookType = string
+
+// Types of webhooks
+const (
+	GITEA      HookType = "gitea"
+	GOGS       HookType = "gogs"
+	SLACK      HookType = "slack"
+	DISCORD    HookType = "discord"
+	DINGTALK   HookType = "dingtalk"
+	TELEGRAM   HookType = "telegram"
+	MSTEAMS    HookType = "msteams"
+	FEISHU     HookType = "feishu"
+	MATRIX     HookType = "matrix"
+	WECHATWORK HookType = "wechatwork"
+	PACKAGIST  HookType = "packagist"
+)
+
+// HookStatus is the status of a web hook
+type HookStatus int
+
+// Possible statuses of a web hook
+const (
+	HookStatusNone HookStatus = iota
+	HookStatusSucceed
+	HookStatusFail
+)