Generalize check figures equal to work with pytest.marks

[weiji14]

Description of proposed changes

Our @check_figures_equal decorator used for comparing two images doesn't work with pytest.mark.parametrize. These are cherry-picked commits from #560.

Changes in this PR are following the cue of matplotlib's check_figures_equal decorator. See matplotlib/matplotlib#15199 and matplotlib/matplotlib#17267.

Note also issue #579 on how we should really just vendor off the check_figures_equal function in the future instead of keeping this bit of code up to date with matplotlib.

Fixes #

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to docstrings or tutorials.

[seisman]

Looks good, but note that the Style Checks is failing.

[weiji14]

Looks good, but note that the Style Checks is failing.

Ah yes, fixed.