Code formatting updates (#4502)

* Editorconfig: Add space_before_self_closing setting

This was a difference between the way dotnet-format and Rider format code. See https://www.jetbrains.com/help/rider/EditorConfig_Index.html

* Editorconfig: Keep 4 spaces indentation for Swagger JSON files

They are all formatted that way, let's keep it like that.

* Apply dotnet-format, mostly white-space related changes

BTCPayServer/Models/StoreViewModels/CheckoutAppearanceViewModel.cs

@@ -20,7 +20,7 @@ namespace BTCPayServer.Models.StoreViewModels
             Languages = new SelectList(choices, nameof(chosen.Value), nameof(chosen.Name), chosen);
             DefaultLang = chosen.Value;
         }
-        
+
         public SelectList Languages { get; set; }
 
         [Display(Name = "Unify on-chain and lightning payment URL/QR code")]
@@ -31,7 +31,7 @@ namespace BTCPayServer.Models.StoreViewModels
 
         [Display(Name = "Use the new checkout")]
         public bool UseNewCheckout { get; set; }
-        
+
         [Display(Name = "Requires a refund email")]
         public bool RequiresRefundEmail { get; set; }
 
@@ -63,7 +63,7 @@ namespace BTCPayServer.Models.StoreViewModels
             }
             [Display(Name = "Enable public receipt page for settled invoices")]
             public bool Enabled { get; set; }
-            
+
             [Display(Name = "Show the QR code of the receipt in the public receipt page")]
             public bool ShowQR { get; set; }