This commit introduces three abstract WebApplicationInitializers, to be
used in the typical setup of a Spring-based web application.
- AbstractContextLoaderInitializer provides an abstract base class for
registering a ContextLoaderListener.
- AbstractDispatcherServletInitializer provides an abstract base class
for registering a DispatcherServlet, with an optional root context.
- AbstractAnnotationConfigDispatcherServletInitializer provides an
abstract base class for registering a DispatcherServlet and optional
ContextLoaderListener based on annotated (e.g. @Configuration)
classes.
Issue: SPR-9300