manage conflict (generic way) use toast to show error (#588)

* manage conflict (generic way) use toast to show error

* fix httpservice after merge conflict, adapt to use new repository

src/BlazorAdmin/Shared/Toast.razor

@@ -0,0 +1,13 @@
+@inherits BlazorAdmin.Helpers.ToastComponent
+
+@namespace BlazorAdmin.Shared
+
+<div class="toast @(IsVisible ? "toast-visible" : null) @BackgroundCssClass">
+    <div class="toast-icon">
+        <i class="fa fa-@IconCssClass" aria-hidden="true"></i>
+    </div>
+    <div class="toast-body">
+        <h5>@Heading</h5>
+        <p>@Message</p>
+    </div>
+</div>