Improve API4 initialization (#18680)

* Improve API4 initialization

- Refactored openGraphDataCache to be inside app layer.
- Moved the cache instance from global variable to be inside server.
- Moved out the app instantiation from the global commands package
to be instantiated on every call. Only the server instance is passed.
- Moved InitLocal to be called from inside Init.

```release-note
NONE
```

* Remove commented line

```release-note
NONE
```

cmd/mattermost/commands/server.go

@@ -93,17 +93,14 @@ func runServer(configStore *config.Store, interruptChan chan os.Signal) error {
 		}
 	}()
 
-	a := app.New(app.ServerConnector(server.Channels()))
-	api := api4.Init(a, server.Router)
-
+	api := api4.Init(server)
 	wsapi.Init(server)
-	web.New(a, server.Router)
-	api4.InitLocal(a, server.LocalRouter)
+	web.New(server)
 
-	serverErr := server.Start()
-	if serverErr != nil {
-		mlog.Critical(serverErr.Error())
-		return serverErr
+	err = server.Start()
+	if err != nil {
+		mlog.Critical(err.Error())
+		return err
 	}
 
 	// If we allow testing then listen for manual testing URL hits

cmd/mattermost/commands/test.go

@@ -58,7 +58,7 @@ func webClientTestsCmdF(command *cobra.Command, args []string) error {
 		return serverErr
 	}
 
-	api4.Init(a, a.Srv().Router)
+	api4.Init(a.Srv())
 	wsapi.Init(a.Srv())
 	a.UpdateConfig(setupClientTests)
 	runWebClientTests()
@@ -79,7 +79,7 @@ func serverForWebClientTestsCmdF(command *cobra.Command, args []string) error {
 		return serverErr
 	}
 
-	api4.Init(a, a.Srv().Router)
+	api4.Init(a.Srv())
 	wsapi.Init(a.Srv())
 	a.UpdateConfig(setupClientTests)