Missing preview images for psfstack and psfalign images

[stscijgbot-jwql]

Issue JWQL-288 was created on JIRA by Bryan Hilbert:

e.g. https://jwql.stsci.edu/MIRI/exposure/jw09056014001_04101_00001/
There are radio buttons for psfstack and psfalign, but no preview images render for them.

We should confirm that these files are actually present, and if so, make sure the preview image generator is able to find them.