libs/utils/test: Add experiment_test decorator
libs/utils/test: Add experiment_test decorator

It's expected that tests often have to iterate over all the experiments
that were run in order to make assertions about the results of
each. This decorator abstracts that iteration, also providing the
experiment workload's task names for convenience.

bjackman/lisa,arnoldlu/lisa,arnoldlu/lisa,credp/lisa,mdigiorgio/lisa,credp/lisa,credp/lisa,bjackman/lisa,joelagnel/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,mdigiorgio/lisa,ARM-software/lisa,joelagnel/lisa,ARM-software/lisa