Make it possible to participate in the component instance creation

The spec requires the implementations to support injection and interception for Servlets, Filters, Listeners and HttpUpgradeHandlers. Still it does not provide any SPI which would allow to participate in the component instance creation.

This is usually not a problem for Java EE servers where integration is mostly based on implementation-specific features.

However, outside Java EE the CDI integration code (for example Weld Servlet) must leverage non-portable SPIs, such as io.undertow.servlet.api.InstanceFactory and org.apache.tomcat.InstanceManager.

It might be useful to provide a portable SPI for this.