Multi product architecture (#3381)

- provides support for compiling Boards directly into the Mattermost suite server
- a ServicesAPI interface replaces the PluginAPI to allow for implementations coming from pluginAPI and suite server.
- a new product package provides a place to register Boards as a suite product and handles life-cycle events
- a new boards package replaces much of the mattermost-plugin logic, allowing this to be shared between plugin and product
- Boards now uses module workspaces; run make setup-go-work

server/utils/callbackqueue.go

@@ -26,11 +26,11 @@ type CallbackQueue struct {
 
 	idone uint32
 
-	logger *mlog.Logger
+	logger mlog.LoggerIFace
 }
 
 // NewCallbackQueue creates a new CallbackQueue and starts a thread pool to service it.
-func NewCallbackQueue(name string, queueSize int, poolSize int, logger *mlog.Logger) *CallbackQueue {
+func NewCallbackQueue(name string, queueSize int, poolSize int, logger mlog.LoggerIFace) *CallbackQueue {
 	cn := &CallbackQueue{
 		name:     name,
 		poolSize: poolSize,