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>

plugin/checker/check_helpers.go

@@ -9,10 +9,10 @@ import (
 	"go/token"
 	"go/types"
 
+	"github.com/pkg/errors"
+
 	"github.com/mattermost/mattermost-server/v5/plugin/checker/internal/asthelpers"
 	"github.com/mattermost/mattermost-server/v5/plugin/checker/internal/version"
-
-	"github.com/pkg/errors"
 )
 
 func checkHelpersVersionComments(pkgPath string) (result, error) {