Move middlewares to web/middleware (#14480)

Co-authored-by: 6543 <6543@obermui.de>

modules/web/middleware/data.go

@@ -0,0 +1,10 @@
+// Copyright 2020 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 middleware
+
+// DataStore represents a data store
+type DataStore interface {
+	GetData() map[string]interface{}
+}