IFRS - Improve file staging error handling (GSI-1190)

[TheByronHimes]

Bumps ifrs version to 2.1.2

The S3 provider in hexkit already checks to make sure the object doesn't exist in the destination bucket, so I removed the same check from the IFRS -- instead, it will catch the corresponding error, log, and return (same behavior as before).

The potential other errors, listed below, are all logged and re-raised:

• The object metadata is missing important info like ContentLength
• The object is over 5 TiB
• Miscellaneous errors in the boto3 copy/multipart upload operation itself