v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/model/scheduled_task_test.go

@@ -0,0 +1,105 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCreateTask(t *testing.T) {
+	TaskName := "Test Task"
+	TaskTime := time.Second * 2
+
+	executionCount := new(int32)
+	testFunc := func() {
+		atomic.AddInt32(executionCount, 1)
+	}
+
+	task := CreateTask(TaskName, testFunc, TaskTime)
+	assert.EqualValues(t, 0, atomic.LoadInt32(executionCount))
+
+	time.Sleep(TaskTime + time.Second)
+
+	assert.EqualValues(t, 1, atomic.LoadInt32(executionCount))
+	assert.Equal(t, TaskName, task.Name)
+	assert.Equal(t, TaskTime, task.Interval)
+	assert.False(t, task.Recurring)
+}
+
+func TestCreateRecurringTask(t *testing.T) {
+	TaskName := "Test Recurring Task"
+	TaskTime := time.Second * 2
+
+	executionCount := new(int32)
+	testFunc := func() {
+		atomic.AddInt32(executionCount, 1)
+	}
+
+	task := CreateRecurringTask(TaskName, testFunc, TaskTime)
+	assert.EqualValues(t, 0, atomic.LoadInt32(executionCount))
+
+	time.Sleep(TaskTime + time.Second)
+
+	assert.EqualValues(t, 1, atomic.LoadInt32(executionCount))
+
+	time.Sleep(TaskTime)
+
+	assert.EqualValues(t, 2, atomic.LoadInt32(executionCount))
+	assert.Equal(t, TaskName, task.Name)
+	assert.Equal(t, TaskTime, task.Interval)
+	assert.True(t, task.Recurring)
+
+	task.Cancel()
+}
+
+func TestCancelTask(t *testing.T) {
+	TaskName := "Test Task"
+	TaskTime := time.Second
+
+	executionCount := new(int32)
+	testFunc := func() {
+		atomic.AddInt32(executionCount, 1)
+	}
+
+	task := CreateTask(TaskName, testFunc, TaskTime)
+	assert.EqualValues(t, 0, atomic.LoadInt32(executionCount))
+	task.Cancel()
+
+	time.Sleep(TaskTime + time.Second)
+	assert.EqualValues(t, 0, atomic.LoadInt32(executionCount))
+}
+
+func TestCreateRecurringTaskFromNextIntervalTime(t *testing.T) {
+	taskName := "Test Recurring Task starting from next interval time"
+	taskTime := time.Second * 3
+
+	var executionTime time.Time
+	var mu sync.Mutex
+	testFunc := func() {
+		mu.Lock()
+		executionTime = time.Now()
+		mu.Unlock()
+	}
+
+	task := CreateRecurringTaskFromNextIntervalTime(taskName, testFunc, taskTime)
+	defer task.Cancel()
+
+	time.Sleep(taskTime)
+	mu.Lock()
+	expectedSeconds := executionTime.Second()
+	mu.Unlock()
+	// Ideally we would expect 0, but in busy CI environments it can lag
+	// by a second. If we see a lag of more than a second, we would need to disable
+	// the test entirely.
+	assert.LessOrEqual(t, expectedSeconds%3, 1)
+
+	assert.Equal(t, taskName, task.Name)
+	assert.Equal(t, taskTime, task.Interval)
+	assert.True(t, task.Recurring)
+}