title: Register OpenIddict entities into DbContext in another way
body: <p>Is there another way to  register the entity sets needed by <code>OpenIddict</code> onto a <code>DbContext</code> except calling 
  <code>options.UseOpenIddict();</code> in <code>services.AddDbContext&lt;OpenIdDictDbContext&gt;(options =&gt; {...})</code>.</p>
  
  <p>I have trouble with this approach, because I have more <code>DbContexts</code>, and I want to share <code>DbContextOptions</code>.</p>
  
  <p>In .Net Core 2, if you can use non generic <code>DbContextOptions</code> for all <code>DbContexts</code> OR you must have nongeneric <code>DbContextOptions&lt;T&gt;</code> for all <code>DbContexts</code>. So, I would like the first approach if it possible.</p>