[bs-28] Add /shutdown endpoint to service apps

Disabled by default use container.allow_shutdown=true to switch
it on.  Then POST to /shutdown to shut down the app.

[#48059059]

spring-bootstrap-samples/spring-bootstrap-service-sample/src/main/resources/application.properties

@@ -1,6 +1,7 @@
 logging.file: /tmp/logs/app.log
 container.port: 8080
 container.management_port: 8080
+container.allow_shutdown: true
 container.tomcat.basedir: target/tomcat
 container.tomcat.access_log_pattern: %h %t "%r" %s %b
 security.require_ssl: false