use cancellation tokens in ui (#666)

* use cancellation tokens in pages

* use cancellation token in shared ui

* use cancellation tokens in artwork controller

ErsatzTV/Pages/JellyfinPathReplacementsEditor.razor

@@ -4,6 +4,8 @@
 @using ErsatzTV.Application.Jellyfin
 @using ErsatzTV.Application.Jellyfin.Commands
 @using Unit = LanguageExt.Unit
+@using System.Threading
+@implements IDisposable
 @inject NavigationManager _navigationManager
 @inject ILogger<ScheduleItemsEditor> _logger
 @inject ISnackbar _snackbar
@@ -17,16 +19,23 @@
     GetPathReplacementsBySourceId="GetPathReplacementsBySourceId"/>
 
 @code {
+    private readonly CancellationTokenSource _cts = new();
 
     [Parameter]
     public int Id { get; set; }
 
-    private Task<Option<RemoteMediaSourceViewModel>> GetMediaSourceById(int id) =>
-        _mediator.Send(new GetJellyfinMediaSourceById(Id))
+    public void Dispose()
+    {
+        _cts.Cancel();
+        _cts.Dispose();
+    }
+
+    private async Task<Option<RemoteMediaSourceViewModel>> GetMediaSourceById(int id) =>
+        await _mediator.Send(new GetJellyfinMediaSourceById(Id), _cts.Token)
             .MapT(vm => new RemoteMediaSourceViewModel(vm.Id, vm.Name, vm.Address));
 
-    private Task<List<RemoteMediaSourcePathReplacementEditViewModel>> GetPathReplacementsBySourceId(int mediaSourceId) =>
-        _mediator.Send(new GetJellyfinPathReplacementsBySourceId(Id))
+    private async Task<List<RemoteMediaSourcePathReplacementEditViewModel>> GetPathReplacementsBySourceId(int mediaSourceId) =>
+        await _mediator.Send(new GetJellyfinPathReplacementsBySourceId(Id), _cts.Token)
             .Map(list => list.Map(ProjectToEditViewModel).ToList());
 
     private RemoteMediaSourcePathReplacementEditViewModel ProjectToEditViewModel(JellyfinPathReplacementViewModel item) =>