Configuration class injected in CE does not provide project specific settings

Custom plugins which implements `org.sonar.api.ce.posttask.PostProjectAnalysisTask` and which would like to read project-specific data are unable to use `org.sonar.api.config.Configuration` class as stated in javadocs.

 * Component to get effective configuration. Values of properties depend on the runtime environment:
 * <ul>
 *   <li>immutable project configuration in scanner.</li>
 *   <li>global configuration in web server. It does not allow to get the settings overridden on projects.</li>
 *   <li>project configuration in Compute Engine.</li>
 * </ul>

Implementation details:
The instance of injected class is `org.sonar.server.config.ConfigurationProvider.ServerConfigurationAdapter`, which holds `org.sonar.server.setting.ThreadLocalSettings` under the hood. This settings does not provide project specific settings.