Add system setting table with cache and also add cache supports for user setting (#18058)

modules/system/item_runtime.go

@@ -0,0 +1,15 @@
+// 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 system
+
+// RuntimeState contains app state for runtime, and we can save remote version for update checker here in future
+type RuntimeState struct {
+	LastAppPath string `json:"last_app_path"`
+}
+
+// Name returns the item name
+func (a RuntimeState) Name() string {
+	return "runtime-state"
+}