feat: add Microservices Load Shedding pattern (#3229) (#3599)

* feat: add Microservices Load Shedding pattern (#3229)

* fix: harden load shedder release and report the admitted count

release() clamps the in-flight count at zero, acquire() returns the admitted count that the service logs, and the demo summary reports the total shed. The class diagram is a rendered PNG.

pom.xml

@@ -260,6 +260,7 @@
     <module>rate-limiting-pattern</module>
     <module>fallback</module>
     <module>onion-architecture</module>
+    <module>microservices-load-shedding</module>
   </modules>
   <repositories>
     <repository>