Switch to @PreAuthorize annotation for blogger UI permission checks

[gmazza]

https://techblog.bozho.net/automate-access-control-for-user-specific-entities/#comment-833474
https://www.roytuts.com/preauthorize-annotation-haspermission-example-in-spring-security/
https://stackoverflow.com/questions/17807586/how-to-use-path-variable-in-preauthorize
https://stackoverflow.com/questions/19525380/difference-between-role-and-grantedauthority-in-spring-security

Less likely:
https://www.logicbig.com/tutorials/spring-framework/spring-web-mvc/spring-handler-interceptor.html
https://stackoverflow.com/questions/39554740/springboot-how-to-return-error-status-code-in-prehandle-of-handlerinterceptor/39555027#39555027

[gmazza]

EntityManager.find() for generic queries by ID: https://github.com/apache/roller/blob/master/app/src/main/java/org/apache/roller/weblogger/business/jpa/JPAPersistenceStrategy.java