Add new API endpoints for push mirrors management (#19841)

- Add a new push mirror to specific repository
- Sync now ( send all the changes to the configured push mirrors )
- Get list of all push mirrors of a repository
- Get a push mirror by ID
- Delete push mirror by ID

Signed-off-by: Mohamed Sekour <mohamed.sekour@exfo.com>
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: zeripath <art27@cantab.net>

modules/structs/mirror.go

@@ -0,0 +1,25 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package structs
+
+// CreatePushMirrorOption represents need information to create a push mirror of a repository.
+type CreatePushMirrorOption struct {
+	RemoteAddress  string `json:"remote_address"`
+	RemoteUsername string `json:"remote_username"`
+	RemotePassword string `json:"remote_password"`
+	Interval       string `json:"interval"`
+}
+
+// PushMirror represents information of a push mirror
+// swagger:model
+type PushMirror struct {
+	RepoName       string `json:"repo_name"`
+	RemoteName     string `json:"remote_name"`
+	RemoteAddress  string `json:"remote_address"`
+	CreatedUnix    string `json:"created"`
+	LastUpdateUnix string `json:"last_update"`
+	LastError      string `json:"last_error"`
+	Interval       string `json:"interval"`
+}