[Feature] Record mode that only records significant differences

[n8chur]

Describe the Issue

It'd be great to have access to a record mode where reference images are only written to disk if the Diffing implementation used considers the difference a failure.

We are currently running snapshot tests on a Intel and M1 machines in my organization (using the Diffing implementation that allows for subpixel precision in #571), and with record mode on today, reference images are saved to disk if there is any difference, regardless of whether the difference would cause a test failure.

We're working around this issue by running the test twice when record mode is requested—once with record mode off, and then again if the test fails with record mode on. It'd be great to avoid needing to run the test twice!