Add an implicit catchall ** sitemap matcher when there is no explicit catchall matcher configured

Because developers frequently forget to add an explicit catchall sitemap matcher at the root level, resulting in servlet container exceptions, the HST will provide a default one if it is not configured explicitly. Thus:

To avoid something like:

SEVERE: Servlet.service() for servlet HstContainerServlet threw exception
org.hippoecm.hst.core.container.ContainerNotFoundException: Resolved
siteMapItem does not contain a ComponentConfiguration that can be
resolved./doesnotexist
at org.hippoecm.hst.core.container.ContextResolvingValve.invoke(ContextResolvingValve.java:135)
at org.hippoecm.hst.core.container.HstSitePipeline$Invocation.invokeNext(HstSitePipeline.java:97)
at org.hippoecm.hst.core.container.SiteResolvingValve.invoke(SiteResolvingValve.java:76)
at org.hippoecm.hst.core.container.HstSitePipeline$Invocation.invokeNext(HstSitePipeline.java:97)
at org.hippoecm.hst.core.container.HstURLValve.invoke(HstURLValve.java:53)
at org.hippoecm.hst.core.container.HstSitePipeline$Invocation.invokeNext(HstSitePipeline.java:97)
at org.hippoecm.hst.core.container.HstSitePipeline.invokeValves(HstSitePipeline.java:66)
at org.hippoecm.hst.core.container.HstSitePipeline.invoke(HstSitePipeline.java:57)
at org.hippoecm.hst.core.container.HstRequestProcessorImpl.processR