svd: performance testing

[fnrizzi]

Script: https://github.com/Pressio/pressio-tools/blob/perf/perf-tests/main_svd.py

Ideally, we should split this into two parts. First, we complete the script to support all scenario we want,
and then we run some scaling tests .

Stage 1: preparing the script

• A: uniform row distribution (already supported)
• B: imbalance the num of rows across ranks according to a distribution
• C: support case for certain subset of ranks having zero rows

Stage 2: run tests

• decide on the size of matrix and number of ranks
• A
• B
• C