[JENKINS-60577] - Prevent the RSS feed in Computer page from returning an error 404 (#4411)

* [JENKINS-60577] Rss Latest Builds for Computer

* [JENKINS-60577] Missing javadoc

* [JENKINS-60577] Add builds from the computer

* Update core/src/main/java/hudson/model/Computer.java

* Apply suggestions from code review

Co-Authored-By: Oleg Nenashev <o.v.nenashev@gmail.com>

* [JENKINS-60577] Document limitation to AbstractProject

* [JENKINS-60577] Restrict the RSS methods in Computer

Co-authored-by: Oleg Nenashev <o.v.nenashev@gmail.com>