[WFLY-543] : Provide an operation to request service status report after server has been started

Adding the new command "read-boot-errors" available from core-service=management to list all operations that failed during boot.
It displays all boot errors with the failed operation and the failure description / exception of the error.
Jira: https://issues.jboss.org/browse/WFLY-543
This isn't really public API so no need to deprecate, just modify the method.