title: Set Sentry Performance Transaction in IActionFilter
body: <p>I want to Start a transaction for every ControllerAction that is hit.</p>
  <p>I made an <code>SentryFilter : IActionFilter</code> and start/finish the transaction in <code>OnActionExecuting</code>/<code>OnActionExecuted</code>. The transaction is started/finished in the filter and sent to Sentry but:</p>
  <p><code>SentrySdk.GetSpan()</code> returns null in the ControllerAction and in the Services the Controller uses.
  If I start the Transaction inside the ControllerAction, <code>SentrySdk.GetSpan()</code> is working in the Service.</p>
  <p>If I do it inside a BaseController, it behaves the same as in the Filter.</p>
  <p>How can I make it work that I dont need to manually start a transaction in every Action?</p>