Add sync_on_commit option for push mirrors api (#22271)

Push mirrors `sync_on_commit` option was added to the web interface in
v1.18.0. However, it's not added to the API. This PR updates the API
endpoint.

Fixes #22267

Also, I think this should be backported to 1.18

modules/structs/mirror.go

@@ -9,6 +9,7 @@ type CreatePushMirrorOption struct {
 	RemoteUsername string `json:"remote_username"`
 	RemotePassword string `json:"remote_password"`
 	Interval       string `json:"interval"`
+	SyncOnCommit   bool   `json:"sync_on_commit"`
 }
 
 // PushMirror represents information of a push mirror
@@ -21,4 +22,5 @@ type PushMirror struct {
 	LastUpdateUnix string `json:"last_update"`
 	LastError      string `json:"last_error"`
 	Interval       string `json:"interval"`
+	SyncOnCommit   bool   `json:"sync_on_commit"`
 }