per-test option cpusPerTask should work with the slurm module

The command line option --cpusPerTask works with the slurm module.
This option will add this to the srun line so it looks like so if run with ats -cpusPerTask=2

srun --nodes=2-3 --cpus-per-task=2 --ntasks=40

However if the cpusPerTask=2 is specified on the ATS test line for an individual test case, it is ignored. That is, this line is generated.

srun --nodes=2-3 --cpus-per-task=1 --ntasks=40

The slurm module should honor that option on a per test basis, so that non threaded codes can reserve 2 CPUs for a test in order to undersubscribe nodes, or for any other reason.

Start in the slurm module and trace how the per-test ATS option is converted into the srun command, comparing it with the command-line --cpusPerTask path. Confirm that a test-level cpusPerTask value changes --cpus-per-task for that test, including the shown value of 2, while preserving the existing command-line behavior.

Written by the indexing model from the issue text.