Extend validation for MARC-files where file-extension was changed from .mrk to .mrc

Overview:

After changing .mrk to .mrc file can`t be uploaded (no actions and logs).

Steps to Reproduce:

1. Log into folio hosted-ref-env with the appropriate creds.
2. Try to upload attached file(1.mrc).

Expected Results:
Import job revealed and it has "Failed"-status.
Actual Results:
No jobs are revealed. There are no information/logs about importing job.

Additional Information:
How to build this file:

1. Open "1_record.mrc" file in MarcEditor.
2. Save it as "1_record_mrk.mrk". (With ".mrk"-extension!)
3. Change name of this file to "1_record_mrk.mrc"(With ".mrc"-extension!)

Moreover, MarcEditor can't open this file. 

Note: There are no errors/exception in logs from BE-side, so it's need investigation of this problem.