Use cmake targets instead of separate usage of libraries/includes. This allows fro a much cleaner approach to the use of dependencies, allows for flag incorporation into the targets, etc.
Add some minimal versions for ROOT, Openloops, etc.
Test Plan
Compilation should pass.
Additional Checklist Items
I have updated documentation as needed
No action needed.
I considered if this should be cherry-picked/ported somewhere else (rel-2-x or master), and if yes, opened a corresponding issue or MR
No action needed.