Refactor webhook events (#33337)

Extract from #33320

This PR uses a map instead of a struct to store webhook event
information. It removes many duplicated functions and makes the logic
clearer.

modules/webhook/events.go

@@ -0,0 +1,20 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package webhook
+
+type HookEvents map[HookEventType]bool
+
+func (he HookEvents) Get(evt HookEventType) bool {
+	return he[evt]
+}
+
+// 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"`
+}