Added IDatabase interface and refactored to use it to handle database type - updated Installer to dynamically add databases to selector

Oqtane.Server/Databases/SqlServerDatabase.cs

@@ -0,0 +1,17 @@
+using Microsoft.EntityFrameworkCore;
+using Oqtane.Interfaces;
+
+namespace Oqtane.Repository.Databases
+{
+    public class SqlServerDatabase : IDatabase
+    {
+        public string FriendlyName => "SQL Server";
+
+        public string Name => "SqlServer";
+
+        public DbContextOptionsBuilder UseDatabase(DbContextOptionsBuilder optionsBuilder, string connectionString)
+        {
+            return optionsBuilder.UseSqlServer(connectionString);
+        }
+    }
+}