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/platform/shared/filestore/filesstore_test.go

@@ -18,7 +18,7 @@ import (
 	"github.com/stretchr/testify/suite"
 	"github.com/xtgo/uuid"
 
-	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/mlog"
 )
 
 func randomString() string {

server/platform/shared/filestore/localstore.go

@@ -12,7 +12,7 @@ import (
 
 	"github.com/pkg/errors"
 
-	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/mlog"
 )
 
 const (

server/platform/shared/filestore/mocks/FileBackend.go

@@ -7,7 +7,7 @@ package mocks
 import (
 	io "io"
 
-	filestore "github.com/mattermost/mattermost-server/v6/server/platform/shared/filestore"
+	filestore "github.com/mattermost/mattermost-server/server/v8/platform/shared/filestore"
 
 	mock "github.com/stretchr/testify/mock"
 

server/platform/shared/filestore/s3store.go

@@ -19,7 +19,7 @@ import (
 	"github.com/minio/minio-go/v7/pkg/encrypt"
 	"github.com/pkg/errors"
 
-	"github.com/mattermost/mattermost-server/v6/server/platform/shared/mlog"
+	"github.com/mattermost/mattermost-server/server/v8/platform/shared/mlog"
 )
 
 // S3FileBackend contains all necessary information to communicate with