* Enable nullable
* Add a fast return to ReportFileSystemChanged when path should be ignored
* Use Span overloads of Path.* functions where possible
* IFileSystem: remove NormalizePath as Path.TrimEndingDirectorySeparator already checks if it's a root path
```
[15:01:24] [ERR] [55] Jellyfin.Server.Middleware.ExceptionMiddleware: Error processing request. URL GET /Environment/Drives.
System.UnauthorizedAccessException: Access to the path is denied.
---> System.IO.IOException: Operation not permitted
--- End of inner exception stack trace ---
at System.IO.DriveInfo.CheckStatfsResultAndThrowIfNecessary(Int32 result)
at System.IO.DriveInfo.get_TotalSize()
at Emby.Server.Implementations.IO.ManagedFileSystem.<>c.<GetDrives>b__32_0(DriveInfo d) in /home/bond/dev/jellyfin/Emby.Server.Implementations/IO/ManagedFileSystem.cs:line 583
at System.Linq.Enumerable.WhereSelectArrayIterator`2.ToList()
at Emby.Server.Implementations.IO.ManagedFileSystem.GetDrives() in /home/bond/dev/jellyfin/Emby.Server.Implementations/IO/ManagedFileSystem.cs:line 583
at Jellyfin.Api.Controllers.EnvironmentController.GetDrives() in /home/bond/dev/jellyfin/Jellyfin.Api/Controllers/EnvironmentController.cs:line 153
at lambda_method559(Closure , Object , Object[] )
at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
```