add .gpg url (match github behaviour) (#6610)

* add .gpg url (match github behaviour)

* wildcard

* test to export maximum data

* working POC

* add comment for old imported keys

* cleaning

* Update routers/user/profile.go

Co-Authored-By: sapk <sapk@users.noreply.github.com>

* add migration script

* add integration tests

models/migrations/v84.go

@@ -0,0 +1,18 @@
+// Copyright 2019 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 migrations
+
+import (
+	"github.com/go-xorm/xorm"
+)
+
+func addGPGKeyImport(x *xorm.Engine) error {
+	type GPGKeyImport struct {
+		KeyID   string `xorm:"pk CHAR(16) NOT NULL"`
+		Content string `xorm:"TEXT NOT NULL"`
+	}
+
+	return x.Sync2(new(GPGKeyImport))
+}