Profile zstash check

[forsyth2]

Summary

Objectives:

• Add performance profiling for zstash check.

Issue resolution:

• Closes [Feature]: Improve efficiency of zstash check #446 (one component. The other component is actually improving the efficiency of zstash check; that is covered by Speed up zstash check multiprocessing scheduling and queue handling #447).
• This is an extension of Add performance profiling as a standard zstash test #427, which is the initial performance profiling.

Select one: This pull request is...

• a bug fix: increment the patch version
• a small improvement: increment the minor version
• a new feature: increment the minor version
• an incompatible (non-backwards compatible) API change: increment the major version

Small Change

• To merge, I will use "Squash and merge". That is, this change should be a single commit.
• Logic: I have visually inspected the entire pull request myself.
• Pre-commit checks: All the pre-commits checks have passed.

[forsyth2]

The first 17 commits are from #427. They will be removed from this PR once that PR is merged and I rebase this branch.

[forsyth2]

Prototype of Fig 3 (check):

Remaining action items:

• Run again, so we have a baseline to use for a check comparison plot.
• Create that check comparison plot.
• Visually inspect code changes
• Merge Add performance profiling as a standard zstash test #427 and rebase this branch off the latest main

[forsyth2]

Prototype of Fig 3b (the comparison) using yesterday's main-branch/Unified baseline and a "current" of the #447's code (the zstash check speedup PR):