Fixed CORE-4651: CREATE DATABASE fails for the user having RDB$ADMIN rights in security database

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@60432 65644016-39b1-43b1-bf79-96bc8fe82c15
Skip system attachmnets in SHOW USERS

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@60433 65644016-39b1-43b1-bf79-96bc8fe82c15
Fixed CORE-4652: Legacy user manager ignores explicitly set SQL role

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@60434 65644016-39b1-43b1-bf79-96bc8fe82c15