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

Oqtane.Shared/Interfaces/IDatabase.cs

@@ -0,0 +1,13 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace Oqtane.Interfaces
+{
+    public interface IDatabase
+    {
+        public string FriendlyName { get; }
+
+        public string Name { get; }
+
+        public DbContextOptionsBuilder UseDatabase(DbContextOptionsBuilder optionsBuilder, string connectionString);
+    }
+}