title: Nebular - How inject custom strategy validations in `getConfigValue()`?
body: <p>Why <code>getConfigValue()</code> function isn't get validation values from custom Strategies?</p>
  <p>Example:</p>
  <pre class="lang-js prettyprint-override"><code>@Injectable()
  export class CustomStrategy extends NbPasswordAuthStrategy {
      protected defaultOptions: CustomStrategyOptions = CustomStrategyOptions;
  
      static setup(options: CustomStrategyOptions): [NbAuthStrategyClass, CustomStrategyOptions] {
          return [CustomStrategy, options];
      }
  }
  </code></pre>
  <pre class="lang-js prettyprint-override"><code>export class CustomStrategyOptions extends NbPasswordAuthStrategyOptions {
      validation?: CustomValidation;
  }
  export const customStrategyOptions: CustomStrategyOptions = new CustomStrategyOptions();
  </code></pre>
  <p>Where <code>CustomValidation</code> class contains different fields than <code>fullName</code>, <code>password</code> and <code>email</code>, for example: <code>name</code>, <code>lastName</code>, <code>date birth</code> and <code>gender</code>.</p>
  <p>In custom <code>RegisterComponent</code> in form inputs if you try this:</p>
  <pre class="lang-js prettyprint-override"><code>export class RegisterComponent extends NbRegisterComponent implements OnInit {
      ngOnInit() {
          console.log('validations', this.getConfigValue('forms.validation');
      }
  }
  </code></pre>
  <p>The output is <code>fullName</code>, <code>password</code> and <code>email</code> :(</p>
  <p>How to inject custom strategy validations in <code>getConfigValue()</code> method in Nebular?</p>