v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/channels/app/teams/helper_test.go

@@ -9,10 +9,10 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/mattermost/mattermost-server/v6/model"
-	"github.com/mattermost/mattermost-server/v6/server/channels/app/request"
-	"github.com/mattermost/mattermost-server/v6/server/channels/store"
-	"github.com/mattermost/mattermost-server/v6/server/config"
+	"github.com/mattermost/mattermost-server/server/v8/channels/app/request"
+	"github.com/mattermost/mattermost-server/server/v8/channels/store"
+	"github.com/mattermost/mattermost-server/server/v8/config"
+	"github.com/mattermost/mattermost-server/server/v8/model"
 )
 
 type TestHelper struct {

server/channels/app/teams/main_test.go

@@ -7,7 +7,7 @@ import (
 	"flag"
 	"testing"
 
-	"github.com/mattermost/mattermost-server/v6/server/channels/testlib"
+	"github.com/mattermost/mattermost-server/server/v8/channels/testlib"
 )
 
 var mainHelper *testlib.MainHelper

server/channels/app/teams/service.go

@@ -6,8 +6,8 @@ package teams
 import (
 	"errors"
 
-	"github.com/mattermost/mattermost-server/v6/model"
-	"github.com/mattermost/mattermost-server/v6/server/channels/store"
+	"github.com/mattermost/mattermost-server/server/v8/channels/store"
+	"github.com/mattermost/mattermost-server/server/v8/model"
 )
 
 type TeamService struct {

server/channels/app/teams/teams.go

@@ -6,8 +6,8 @@ package teams
 import (
 	"context"
 
-	"github.com/mattermost/mattermost-server/v6/model"
-	"github.com/mattermost/mattermost-server/v6/server/platform/shared/i18n"
+	"github.com/mattermost/mattermost-server/server/v8/model"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/i18n"
 )
 
 func (ts *TeamService) CreateTeam(team *model.Team) (*model.Team, error) {

server/channels/app/teams/teams_test.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/stretchr/testify/require"
 
-	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/server/v8/model"
 )
 
 func TestCreateTeam(t *testing.T) {

server/channels/app/teams/utils.go

@@ -6,7 +6,7 @@ package teams
 import (
 	"strings"
 
-	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/server/v8/model"
 )
 
 // By default the list will be (not necessarily in this order):