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/templates/templates.go

@@ -13,7 +13,7 @@ import (
 
 	"github.com/fsnotify/fsnotify"
 
-	"github.com/mattermost/mattermost-server/server/v8/channels/utils/fileutils"
+	"github.com/mattermost/mattermost/server/v8/channels/utils/fileutils"
 )
 
 // Container represents a set of templates that can be render