Added suuport to inject an IOqtaneDatabase in EntityBuilders to allow each Database to control certain Migration behaviors. Also updated Installer to dynamically build Database Configuration section

Oqtane.Server/Repository/Context/DbConfig.cs

@@ -1,20 +1,25 @@
+using System.Collections.Generic;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Configuration;
+using Oqtane.Interfaces;
 
 namespace Oqtane.Repository
 {
     public class DbConfig : IDbConfig
     {
-        public DbConfig(IHttpContextAccessor accessor, IConfiguration configuration)
+        public DbConfig(IHttpContextAccessor accessor, IConfiguration configuration, IEnumerable<IOqtaneDatabase> databases)
         {
             Accessor = accessor;
             Configuration = configuration;
+            Databases = databases;
         }
 
         public IHttpContextAccessor Accessor { get; }
 
         public IConfiguration Configuration { get; }
 
+        public IEnumerable<IOqtaneDatabase> Databases { get; set; }
+
         public string ConnectionString { get; set; }
 
         public string DatabaseType { get; set; }