added logging for startup issues

Oqtane.Server/Infrastructure/Logging/FileLoggerProvider.cs

@@ -0,0 +1,30 @@
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Oqtane.Infrastructure
+{
+    /// <summary>
+    /// FileLogger should only be used in scenarios where a database is not available or tenant/site cannot be determined ( ie. during startup )
+    /// </summary>
+    [ProviderAlias("FileLogger")]
+    public class FileLoggerProvider : ILoggerProvider
+    {
+        private readonly IWebHostEnvironment _environment;
+        private readonly IConfigManager _configManager;
+
+        public FileLoggerProvider(IWebHostEnvironment environment, IConfigManager configManager)
+        {
+            _environment = environment;
+            _configManager = configManager;
+        }
+
+        public ILogger CreateLogger(string categoryName)
+        {
+            return new FileLogger(this, _environment, _configManager);
+        }
+
+        public void Dispose()
+        {
+        }
+    }
+}