refactor(Program): update to scan all appsettings.*.json's

EnvelopeGenerator.Web/Program.cs

@@ -34,6 +34,12 @@ try
 
     var config = builder.Configuration;
 
+    Directory
+        .GetFiles(builder.Environment.ContentRootPath, "appsettings.*.json", SearchOption.TopDirectoryOnly)
+        .Where(file => Path.GetFileName(file) != $"appsettings.Development.json")
+        .ToList()
+        .ForEach(file => config.AddJsonFile(file, true, true));
+
     var allowedOrigins = config.GetSection("AllowedOrigins").Get<string[]>() ??
         throw new InvalidOperationException("AllowedOrigins section is missing in the configuration.");