Support --benchmark-id when running `oscap generate guide`
Support --benchmark-id when running `oscap generate guide`

This allows us to select a benchmark with source datastreams having more
than one XCCDF benchmark in them.

Hexadorsimal/openscap,ybznek/openscap,jan-cerny/openscap,mpreisler/openscap,mpreisler/openscap,OpenSCAP/openscap,mpreisler/openscap,redhatrises/openscap,OpenSCAP/openscap,redhatrises/openscap,jan-cerny/openscap,redhatrises/openscap,OpenSCAP/openscap,redhatrises/openscap,jan-cerny/openscap,ybznek/openscap,OpenSCAP/openscap,Hexadorsimal/openscap,ybznek/openscap,redhatrises/openscap,Hexadorsimal/openscap,ybznek/openscap,Hexadorsimal/openscap,Hexadorsimal/openscap,OpenSCAP/openscap,jan-cerny/openscap,ybznek/openscap,ybznek/openscap,jan-cerny/openscap,Hexadorsimal/openscap,mpreisler/openscap,mpreisler/openscap,mpreisler/openscap,OpenSCAP/openscap,redhatrises/openscap,jan-cerny/openscap