Handle empty zip itemName in NetcdfFiles.makeUncompressed

[rschmunk]

Description of Changes

Trap for case of no (empty) itemName appended to file path when a zip is passed to NetcdfFiles to uncompress and open. See #1307.

PR Checklist

• [x] Link to any issues that the PR addresses
• [ ] Add labels
• [x] Open as a draft PR until ready for review
• [x] Make sure GitHub tests pass
• [x] Mark PR as "Ready for Review"