title: provideDebugConfigurations not getting called
body: <p>I am using the vscode-mock-debug git as the basis for my work.</p>
  
  <p>Activation event is OnDebug, although same result</p>
  
  <p>I implement provideDebugConfigurations in my DebugConfigurationProvider and its not getting called.</p>
  
  <pre><code>provideDebugConfigurations(folder: WorkspaceFolder | undefined, token?: CancellationToken): DebugConfiguration[] {
   return [...my data in here];
  }
  </code></pre>
  
  <p>the resolveDebugConfiguration (the original from mock-debug) is called, I can set a breakpoint. However the provideDebugConfigurations is never getting reached. build 1.36 of vsce. am I missing something obvious ?</p>