Add Azure implementation for retrieve access token

...re/src/main/java/org/opendes/indexer/azure/api/Hello.java

...org/opendes/indexer/azure/security/AADSecurityConfig.java

.../org/opendes/indexer/azure/security/WhoamiController.java

.../java/org/opendes/indexer/azure/util/RequestInfoImpl.java

...endes/indexer/azure/util/ServiceAccountJwtClientImpl.java

indexer-service-azure/src/main/resources/logback-spring.xml