ingest of tsv fails in direct upload

[qqmyers]

Trying direct upload of .tsv file via direct upload to s3 failed to trigger ingest. Investigating showed two issues:

• My browser did not assign a mimetype to .tsv files during upload so it was being processed as application-octet-stream. Adding code to at least detect the mimetype via fileExtension (a partial solution to 6762) helped, but assigned the mimetype text/tab-separated-values to the file.
• Looking into that it appears that the changes in disables ingest of filetype text/tab-separated-values #6517 to reserve the text/tab-separated-values type for ingested .tab files did not catch the assignment of tsv to that mimetype in META-INF/mime.types. Changing the assignment there to use text/tsv as the mimetype allows the .tsv file to be ingested.

PR to follow.