MM-8708 Remove api package (#8784)

* Remove api package

* Remove api dependency from cmd package

* Remove EnableAPIv3 setting

* Update web tests

* Add more websocket tests

* Move some ws and oauth tests to api4 package

* Move command tests into api4 package

* Test fixes

* Fix msg command test

* Add some app file tests

model/config.go

@@ -184,7 +184,6 @@ type ServiceSettings struct {
 	EnableOnlyAdminIntegrations                       *bool
 	EnablePostUsernameOverride                        bool
 	EnablePostIconOverride                            bool
-	EnableAPIv3                                       *bool
 	EnableLinkPreviews                                *bool
 	EnableTesting                                     bool
 	EnableDeveloper                                   *bool
@@ -244,10 +243,6 @@ func (s *ServiceSettings) SetDefaults() {
 		s.ListenAddress = NewString(SERVICE_SETTINGS_DEFAULT_LISTEN_AND_ADDRESS)
 	}
 
-	if s.EnableAPIv3 == nil {
-		s.EnableAPIv3 = NewBool(true)
-	}
-
 	if s.EnableLinkPreviews == nil {
 		s.EnableLinkPreviews = NewBool(false)
 	}