Fix failing tests and improve test scripts

[markcmiller86]

Description

This should fix the failing tests for annot_macros.py. Instead of adding anything to skip lists, etc, I just added a very small pixdiff to the two cases where tests were failing.

I also improved output from --help and improved html rendering of diff metrics.

Type of change

• [ ] Bug fix~~
• [ ] New feature~~
• [ ] Documentation update~~
• [x] Other: fuzzy match a couple tests that have some variability

How Has This Been Tested?

I ran locally and they pass.

Reminders:

• Please follow the style guidelines of this project.
• Please perform a self-review of your code before submitting a PR and asking others to review it.
• Please assign reviewers (see VisIt's PR procedures for more information).

Checklist:

• [x] I have commented my code where applicable.~~
• [ ] I have updated the release notes.
• [ ] I have made corresponding changes to the documentation.
• [x] I have added debugging support to my changes.~~
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [x] I have confirmed new and existing unit tests pass locally with my changes.~~
• [ ] I have added new baselines for any new tests to the repo.
• [x] I have NOT made any changes to protocol or public interfaces in an RC branch.~~