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>

app/upload_test.go

@@ -13,10 +13,10 @@ import (
 	"sync/atomic"
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/utils/fileutils"
-
-	"github.com/stretchr/testify/require"
 )
 
 func TestCreateUploadSession(t *testing.T) {