Move migrating repository from frontend to backend (#6200)

* move migrating to backend

* add loading image when migrating and fix tests

* fix format

* fix lint

* add redis task queue support and improve docs

* add redis vendor

* fix vet

* add database migrations and fix app.ini sample

* add comments for task section on app.ini.sample

* Update models/migrations/v84.go

Co-Authored-By: lunny <xiaolunwen@gmail.com>

* Update models/repo.go

Co-Authored-By: lunny <xiaolunwen@gmail.com>

* move migrating to backend

* add loading image when migrating and fix tests

* fix fmt

* add redis task queue support and improve docs

* fix fixtures

* fix fixtures

* fix duplicate function on index.js

* fix tests

* rename repository statuses

* check if repository is being create when SSH request

* fix lint

* fix template

* some improvements

* fix template

* unified migrate options

* fix lint

* fix loading page

* refactor

* When gitea restart, don't restart the running tasks because we may have servel gitea instances, that may break the migration

* fix js

* Update models/repo.go

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Update docs/content/doc/advanced/config-cheat-sheet.en-us.md

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* fix tests

* rename ErrTaskIsNotExist to ErrTaskDoesNotExist

* delete release after add one on tests to make it run happy

* fix tests

* fix tests

* improve codes

* fix lint

* fix lint

* fix migrations

modules/task/queue_channel.go

@@ -0,0 +1,48 @@
+// 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 task
+
+import (
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/log"
+)
+
+var (
+	_ Queue = &ChannelQueue{}
+)
+
+// ChannelQueue implements
+type ChannelQueue struct {
+	queue chan *models.Task
+}
+
+// NewChannelQueue create a memory channel queue
+func NewChannelQueue(queueLen int) *ChannelQueue {
+	return &ChannelQueue{
+		queue: make(chan *models.Task, queueLen),
+	}
+}
+
+// Run starts to run the queue
+func (c *ChannelQueue) Run() error {
+	for task := range c.queue {
+		err := Run(task)
+		if err != nil {
+			log.Error("Run task failed: %s", err.Error())
+		}
+	}
+	return nil
+}
+
+// Push will push the task ID to queue
+func (c *ChannelQueue) Push(task *models.Task) error {
+	c.queue <- task
+	return nil
+}
+
+// Stop stop the queue
+func (c *ChannelQueue) Stop() {
+	close(c.queue)
+}