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/structs.go

@@ -0,0 +1,38 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package webhook
+
+// HookEvents is a set of web hook events
+type HookEvents struct {
+	Create               bool `json:"create"`
+	Delete               bool `json:"delete"`
+	Fork                 bool `json:"fork"`
+	Issues               bool `json:"issues"`
+	IssueAssign          bool `json:"issue_assign"`
+	IssueLabel           bool `json:"issue_label"`
+	IssueMilestone       bool `json:"issue_milestone"`
+	IssueComment         bool `json:"issue_comment"`
+	Push                 bool `json:"push"`
+	PullRequest          bool `json:"pull_request"`
+	PullRequestAssign    bool `json:"pull_request_assign"`
+	PullRequestLabel     bool `json:"pull_request_label"`
+	PullRequestMilestone bool `json:"pull_request_milestone"`
+	PullRequestComment   bool `json:"pull_request_comment"`
+	PullRequestReview    bool `json:"pull_request_review"`
+	PullRequestSync      bool `json:"pull_request_sync"`
+	Wiki                 bool `json:"wiki"`
+	Repository           bool `json:"repository"`
+	Release              bool `json:"release"`
+	Package              bool `json:"package"`
+}
+
+// HookEvent represents events that will delivery hook.
+type HookEvent struct {
+	PushOnly       bool   `json:"push_only"`
+	SendEverything bool   `json:"send_everything"`
+	ChooseEvents   bool   `json:"choose_events"`
+	BranchFilter   string `json:"branch_filter"`
+
+	HookEvents `json:"events"`
+}