MM-53032: Fix module path after repo rename (#23689)

It was a good decision in hindsight to keep the public module as 0.x
because this would have been a breaking change again.

https://mattermost.atlassian.net/browse/MM-53032
```release-note
Changed the Go module path from github.com/mattermost/mattermost-server/server/v8 to github.com/mattermost/mattermost/server/v8.

For the public facing module, it's path is also changed from github.com/mattermost/mattermost-server/server/public to github.com/mattermost/mattermost/server/public
```

server/platform/shared/filestore/filesstore.go

@@ -8,7 +8,7 @@ import (
 	"io"
 	"time"
 
-	"github.com/mattermost/mattermost-server/server/public/model"
+	"github.com/mattermost/mattermost/server/public/model"
 	"github.com/pkg/errors"
 )
 

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/server/public/shared/mlog"
+	"github.com/mattermost/mattermost/server/public/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/server/public/shared/mlog"
+	"github.com/mattermost/mattermost/server/public/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/server/v8/platform/shared/filestore"
+	filestore "github.com/mattermost/mattermost/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/server/public/shared/mlog"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 )
 
 // S3FileBackend contains all necessary information to communicate with

server/platform/shared/filestore/s3store_test.go

@@ -18,7 +18,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/mattermost/mattermost-server/server/public/model"
+	"github.com/mattermost/mattermost/server/public/model"
 	s3 "github.com/minio/minio-go/v7"
 	"github.com/stretchr/testify/require"
 )