MM-36271: Bump major version to 6.0 (#17973)

https://mattermost.atlassian.net/browse/MM-36271

```release-note
We bump the major version to 6.0
```

services/remotecluster/invitation.go

@@ -8,7 +8,7 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v6/model"
 )
 
 // AcceptInvitation is called when accepting an invitation to connect with a remote cluster.

services/remotecluster/mocks_test.go

@@ -12,12 +12,12 @@ import (
 
 	"go.uber.org/zap/zapcore"
 
-	"github.com/mattermost/mattermost-server/v5/einterfaces"
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/plugin/plugintest/mock"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
-	"github.com/mattermost/mattermost-server/v5/store"
-	"github.com/mattermost/mattermost-server/v5/store/storetest/mocks"
+	"github.com/mattermost/mattermost-server/v6/einterfaces"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/plugin/plugintest/mock"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/store"
+	"github.com/mattermost/mattermost-server/v6/store/storetest/mocks"
 )
 
 type mockServer struct {

services/remotecluster/ping.go

@@ -8,8 +8,8 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 )
 
 // pingLoop periodically sends a ping to all remote clusters.

services/remotecluster/ping_test.go

@@ -15,7 +15,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"github.com/wiggin77/merror"
 
-	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v6/model"
 )
 
 const (

services/remotecluster/recv.go

@@ -6,8 +6,8 @@ package remotecluster
 import (
 	"fmt"
 
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 )
 
 // ReceiveIncomingMsg is called by the Rest API layer, or websocket layer (future), when a Remote Cluster

services/remotecluster/send_test.go

@@ -18,7 +18,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"github.com/wiggin77/merror"
 
-	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v6/model"
 )
 
 const (

services/remotecluster/sendfile.go

@@ -13,9 +13,9 @@ import (
 	"path"
 	"time"
 
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/shared/filestore"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/filestore"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 )
 
 type SendFileResultFunc func(us *model.UploadSession, rc *model.RemoteCluster, resp *Response, err error)

services/remotecluster/sendmsg.go

@@ -17,8 +17,8 @@ import (
 
 	"github.com/wiggin77/merror"
 
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 )
 
 type SendMsgResultFunc func(msg model.RemoteClusterMsg, rc *model.RemoteCluster, resp *Response, err error)

services/remotecluster/sendprofileImage.go

@@ -15,8 +15,8 @@ import (
 	"path"
 	"time"
 
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 )
 
 type SendProfileImageResultFunc func(userId string, rc *model.RemoteCluster, resp *Response, err error)

services/remotecluster/sendprofileImage_test.go

@@ -19,7 +19,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v6/model"
 )
 
 const (

services/remotecluster/service.go

@@ -10,10 +10,10 @@ import (
 	"sync"
 	"time"
 
-	"github.com/mattermost/mattermost-server/v5/einterfaces"
-	"github.com/mattermost/mattermost-server/v5/model"
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
-	"github.com/mattermost/mattermost-server/v5/store"
+	"github.com/mattermost/mattermost-server/v6/einterfaces"
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/store"
 )
 
 const (

services/remotecluster/service_test.go

@@ -10,7 +10,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v6/model"
 )
 
 func TestService_AddTopicListener(t *testing.T) {