Fixing system messages about non-visible users (#14254)

* Fixing system messages about non-visible users

* Adding unit tests to verify the new behavior

* Regenerating app layers

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

app/app_iface.go

@@ -463,6 +463,7 @@ type AppIface interface {
 	FileExists(path string) (bool, *model.AppError)
 	FillInChannelProps(channel *model.Channel) *model.AppError
 	FillInChannelsProps(channelList *model.ChannelList) *model.AppError
+	FilterUsersByVisible(viewer *model.User, otherUsers []*model.User) ([]*model.User, *model.AppError)
 	FindTeamByName(name string) bool
 	GenerateMfaSecret(userId string) (*model.MfaSecret, *model.AppError)
 	GeneratePublicLink(siteURL string, info *model.FileInfo) string