When a file is uploaded for data import, the file extension check should be case-INsensitive

Overview: File extension settings (in Settings/Data import) control which files are permitted for import, and what type of job profiles are displayed (MARC or EDIFACT) on the "job profile selection" screen. When a file extension setting is created, and a file with that extension is uploaded, Data Import should ignore the case of the extension.

Current workaround: change the file extension to a case that matches the file extension setting

Steps to Reproduce:

1. Log into FOLIO-snapshot-load as diku_admin
2. Go to Settings/Data import/File extensions
3. Confirm that there is a file extension setting for .png that disallows that file type from being imported
4. Go to the Data Import landing page
5. Upload the attached file with .png setting
6. Assuming that Data Import disallows the file, then try to upload the attached file with .PNG setting

Expected Results: Because of the .png file extension setting, files with an extension of .png or .PNG should be blocked from being imported

Actual Results: The lower-case file extension was blocked. The upper-case file extension was not

Additional Information: See attached video