Rework AMG experiments

[pearce8]

Types of experiments

• [x] The current Problem 1 experiment should be named "throughput" (varying the size of the problem, keeping resources the same). x-axis label: problem size. Add plots here.
• [x] Add a strong scaling experiment. x-axis label: number of GPUs. Add plots here.
• [x] Write a weak scaling experiment. x-axis label: number of GPUs. Add plots here.
• [x] Add corresponding experiments for Problem 2 (throughput, strong, weak)

What is working:

• [x] CUDA on lassen
• [x] ROCM on tioga
• [x] OpenMP on ruby: throughput works, need params for strong and weak