goimports (#16640)

* format using `goimports -local github.com/mattermost/mattermost-server/v5 -w`

* added goimports lint check to .golangci.yml

* format using `goimports -local github.com/mattermost/mattermost-server/v5 -w` for a corner case

* make app-layers, *-mocks and store-layers for ci check

Co-authored-by: Mahmudul Haque <mahmudulhaque@protonmail.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

web/web_test.go

@@ -13,6 +13,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
 	"github.com/mattermost/mattermost-server/v5/app"
 	"github.com/mattermost/mattermost-server/v5/config"
 	"github.com/mattermost/mattermost-server/v5/mlog"
@@ -23,8 +26,6 @@ import (
 	"github.com/mattermost/mattermost-server/v5/store/storetest/mocks"
 	"github.com/mattermost/mattermost-server/v5/testlib"
 	"github.com/mattermost/mattermost-server/v5/utils"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
 var ApiClient *model.Client4