Refactor BaseUrl and ApiUrl configuration handling.

Updated to use `Http:BaseUrl` for backward compatibility with `Hosting:BaseUrl`. Simplified ApiUrl construction by removing redundant configuration keys and standardizing the behavior using `ApiPrefix`.

src/apps/Elsa.ServerAndStudio.Web/Pages/_Host.cshtml

@@ -2,8 +2,8 @@
 @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
 @inject IConfiguration Configuration;
 @{
-    var baseUrl = Configuration["Hosting:BaseUrl"]!;
-    var apiUrl = Configuration["Hosting:ApiUrl"]!;
+    var baseUrl = Configuration["Hosting:BaseUrl"] ?? Configuration["Http:BaseUrl"]!; // HttpBaseUrl is for backward compatibility.
+    var apiUrl = $"{baseUrl.TrimEnd('/')}/{(Configuration["Hosting:ApiPrefix"] ?? "elsa/api").TrimStart('/')}";
 }
 
 <!DOCTYPE html>
@@ -51,8 +51,7 @@
 <script src="@baseUrl/_content/Radzen.Blazor/Radzen.Blazor.js"></script>
 <script>
     window.getClientConfig = function() { return {
-        "apiUrl": "@apiUrl",
-        "baseUrl": "@baseUrl"
+        "apiUrl": "@apiUrl"
      } };
 </script>
 <script src="@baseUrl/_framework/blazor.webassembly.js"></script>

src/apps/Elsa.ServerAndStudio.Web/Program.cs

@@ -132,7 +132,7 @@ services
 
                 http.ConfigureHttpOptions = options =>
                 {
-                    options.BaseUrl = new Uri(configuration["Hosting:BaseUrl"]!);
+                    options.BaseUrl = new Uri(configuration["Hosting:BaseUrl"] ?? configuration["Http:BaseUrl"]!); // HttpBaseUrl is for backward compatibility.
                     options.BasePath = configuration["Http:BasePath"];
                 };
             })

src/apps/Elsa.ServerAndStudio.Web/appsettings.json

@@ -18,7 +18,7 @@
   "DatabaseProvider": "Sqlite",
   "Hosting": {
     "BaseUrl": "https://localhost:8080",
-    "ApiUrl": "https://localhost:8080/elsa/api"
+    "ApiPrefix": "/elsa/api"
   },
   "Identity": {
     "Tokens": {