Drive: test bad mime type detected by the client and sent to the server

In some cases, the call to mimetypes.guess_type(filename) in base_automation_client.upload() returns a bad mime type.
For example, on Windows, the mime type guesser uses the registry and might return "pdf" instead of "application/pdf", don't really know why...

Since NXP-13036 the WebEngineServlet should detect this and patch the "X-File-Type" HTTP header to add the missing "application/" part if missing, thus avoiding:

[org.nuxeo.ecm.automation.server.jaxrs.batch.BatchResource] Error while executing automation batch
...
Caused by: javax.mail.internet.ParseException: Expected '/', got null
at javax.mail.internet.ContentType.<init>(ContentType.java:102)
at org.nuxeo.drive.operations.NuxeoDriveOperationHelper.normalizeMimeTypeAndEncoding(NuxeoDriveOperationHelper.java:55)
...