GuestLog - User message improvements

- Added UserMessageService to have common methods for showing messages and errors to the user.
- Added Result record so services can return status on operation error (so it can be shown in the UI messages).
- Updated services to use the new Result record.
- Updated pages to use the new IUserMessageService.

src/Somnia.GuestLog/Components/Pages/GuestDocuments/GuestDocDetail.razor

@@ -4,7 +4,7 @@
 @using Somnia.GuestLog.Services;
 @using Microsoft.AspNetCore.WebUtilities;
 
-@inject ISnackbar Snackbar
+@inject IUserMessageService userMessage
 @inject IDialogService DialogService
 @inject NavigationManager Navigation
 @inject IGuestDocumentService guestDocService
@@ -92,7 +92,7 @@
     {
         if (docId is null)
         {
-            Snackbar.Add("No GuestDocument provided!!", Severity.Error);
+            userMessage.ShowMessage("No GuestDocument provided!!", MessageKind.Error);
             Navigation.NotFound();
             return;
         }
@@ -100,7 +100,7 @@
         GuestDocIdDTO? docIdModel = GuestDocIdDTO.DecodeFromString(docId);
         if (docIdModel is null)
         {
-            Snackbar.Add($"Provided GuestDocId can't be decoded: '{docId}'", Severity.Error);
+            userMessage.ShowMessage($"Provided GuestDocId can't be decoded: '{docId}'", MessageKind.Error);
             Navigation.NotFound();
             return;
         }
@@ -109,7 +109,7 @@
         documentModel = await guestDocService.GetDtoByIdAsync(docIdModel.DocumentType, docIdModel.DocumentNum);
         if (documentModel is null)
         {
-            Snackbar.Add($"GuestDocument not found with ID: '{docId}'", Severity.Error);
+            userMessage.ShowMessage($"GuestDocument not found with ID: '{docId}'", MessageKind.Error);
             Navigation.NotFound();
             return;
         }
@@ -138,7 +138,7 @@
 
     private void BtnEdit()
     {
-        Snackbar.Add("Not implemented yet!", Severity.Info);
+        userMessage.ShowMessage("Not implemented yet!", MessageKind.Info);
     }
 
     private void BtnReturn()